Acadia National Park

You will love Acadia!
There are numerous hikes, around the island, including our fave, which is going up the Gorham Trail, where you will be rewarded with fabulous views of the sea on your way up. But there are plenty to choose from.
You can bike the carriage trails, and access them through various entrances.
This is a helpful website. https://acadiamagic.com/. Also nps.gov.

Staying in Bar Harbor will allow you to explore the many restaurants in town. There are a few Italian restaurants in town, all of which we've eaten at over the years. All seemed fine, but none extraordinary.
Again, there are pizza places, and all the usual types of fare around BH, and plenty of ice cream to be had.

We like to have lunch sometimes at the Bar Harbor Inn, and sit outside and watch the sailboats come and go. I enjoy their lobster salad. You might try Thurston's in Bernard, which is quite busy all the times we've been. It sits right on the tiny harbor, and is extremely picturesque. Parking is very tight. Famous for its lobster dishes.

Mount Desert Island and the Park are so beautiful and there is so much to do. Jordan Pond House is a must visit...their popovers are legendary, served on the lawn (Adirondack chairs optional). They also have a restaurant. There is a hiking trail around the pond, if you want to earn your popover.

Trenton Bridge Lobster Pound is well priced, casual eat-in, takeout. Also Thurstons Lobster Pound. These are quintessential Maine casual food spots.

Also, look into the park ranger tours of nearby islands, the Cranberry Islands, for example.

One of my favorite places ever!
I have visited numerous times over the years. My main focus is hiking, and I have used this book to decide on hikes:
https://www.amazon.com/gp/aw/d/149301661X/ref=tmm_pap_title_0?ie=UTF8&qid=1553616144&sr=8-2

Some of my favorite restaurants:
Burning Tree
Cafe This Way
Red Sky (Southwest Harbor)

My favorite lobster pound/shack
Trenton Bridge

Happy to answer additional questions.

If you find yourselves in Brewer (across the river from Bangor) either coming or going, keep the Eagle's Nest in mind as a place to eat.

For less-typical things to do in the park, I'd recommend the Asticou Azalea Garden, which should be great in late June, and Acadia NP east, which is on the Schoodic Peninsula (one peninsula east of Mt. Desert Island). This has good hiking and biking, great scenery, and about 10% of the tourists as the main part of the park.

https://www.mainetrailfinder.com/trails/trail/acadia-national-park-schoodic-bike-paths

In Ellsworth, the Union River Lobster Pot restaurant has a really good "shore dinner"--lobster, steamers, mussels etc.

We camped at Seawall. Make sure to get over to that area as well. We went to a very busy and wonderful seafood restaurant in Bass Harbor. It's been a while, don't know the name of it or if its still there. It was quite large and very popular. There also is a pretty lighthouse in that area. We did a lot of the park hikes. Try to get to the trailheads earlier in the morning to get parking. We did a NPS boat trip which was super fun. Ask the NPS staff about possible tide pooling. We did some hiking on the carriage roads. We liked some of the smaller communities for exploring better than Bar Harbor. We visited some of the gardens affiliated with the Land & Garden Preserve. It's beautiful there, enjoy.

I suggest getting an early start in order to get out ahead of the crowds in the park, which does fill up with day trippers around midday making it difficult to find parking at some of the more popular trailheads.

The town of Bar Harbor tends to get pretty crowded too, especially on days when the cruise ships are in (ie most days). Getting out of town early and returning in the late afternoon or early evening would be a good strategy to enjoy the park and the town.
As the others have said, the park is an absolute jewel - one of the best in the NPS - but it does tend to get loved to death during the height of the summer rush.

Thanks, all who have replied thus far! Keep 'em coming! :)

Any fishing recommendations, either shore- or boat-based? Bike rental places?

There are a number of bike and kayak places along Cottage Street in BH. Have used more than one, and found them all good.

Rent bikes and ride the carriage roads. Pick blueberries if they're ripe yet...might be a little early.
Go sailing.
Go puffin watching.
Go to a town concert at the main bandstand in Bar Harbor.
Hike to the top of Cadillac Mountain - views forever!

Acadia is considered timed-entry for autos to relieve congestion. https://www.nationalparkstraveler.org/2019/03/traffic-management-plan-acadia-national-park-calls-timed-entry-reservations

Thanks, @Carol! I could not yet find a way to reserve a time for us to visit, so I guess that will be up and running in the future. We would fall in the time slot they mentioned (2nd Friday in June thru September). We do plan on biking a lot anyway, but would probably use the car at least the first day to get oriented.

Might add that there's more to Mount Desert Island than BH and the park. If you'd like a break from the crowds consider driving over to the other side of the island to Southwest Harbor - lots of great hiking trails over there too.
If you're up for a longer excursion a bit further afield you might consider a visit to the Roosevelt compound at Campobello, just across the border in New Brunswick - about a 2 hour drive. You'll need your passports.

There is also a free shuttle through the park. We found it helpful for a one-way hike.

More of a hiker than a biker, but would much rather bike on the extensive and car-free carriage road system rather than the sometimes crowded roads.

So I messaged the park on Facebook and they responded that the timed entry does not go into effect this summer. It did not seem clear exactly as to when all the changes will go into effect and the document they put out about it is over 200 pages long.

A few years ago we rented bikes to ride the carriage roads from Southwest Cycle in Southwest Harbor, Maine. I believe we stayed 2 nights in Southwest Harbor; it was much quieter than Bar Harbor. And when in Bar Harbor, we accessed the park from the shuttle bus. Great hiking! We find hiking on the east coast to be much different than hiking on the west coast -- they seem to go up and over a rock or hill rather than create switchbacks or trails around it. Lots of fun!

We love McKay’s Public House for dinner in Bar Harbor.

MDI & Acadia National Park -- been going there since I was a preteen! Ideas off the top of my head in no particular order:

1. Buy a pass for Acadia National Park at the visitor's center and get maps (hiking trails, road) fo all in your party.

2. Drive (or hike if you're in great shape) to the top of Mt Cadillac. If you want to see sunrise first on the US east coast, set the alarm for 3:30am and drive up. Bring a jacket/scarf/gloves.

3. Take a walk on the Wonderland trail. It's easy.

4. Walk along the Seawall. It's near Wonderland.

5. Visit Thunder Hole during high tide.

6. Dip your feet in the ocean or go for a quick swim at Sand Beach.

7. Visit Bass Harbor Light at sunset

8. Have dinner at Thurston's Lobster Pound in Bernard (near Bass Harbor Light). We think it's the best in terms of view and lobster on all of MDI.

9. Go on a whale watch off Bar Harbor

10. See the view of the Bubbles at Jordan Pond and walk around the trails.

11. Go cycling along the Carriage Roads. Many places to rent bikes in Bar Harbor.

12. Take a drive to the Schoodic Peninsula. So worth it and you won't be inundated with tourists.

13. Walk around Echo Lake

14. Go out for breakfast at Everyday Joe's.

15. Do a quick peruse at Sherman's bookstore

Agree with the above list. Jordan pond was very nice. We did Diver Ed's boat tour out of a town just north (??) of Bar Harbor. It was booked thru the park. It was wonderful. We saw seals and other ocean mammals and the divers picked up many sea creatures from the ocean floor and brought them up for folks to view and hold. Educational and very fun!

Use the Island Explorer shuttle bus instead of trying to drive around the park. Traffic in the summer can be horrific, especially around Sand Beach. The Abbe Museum in Bar Harbor is a small but interesting museum featuring the local Native American tribes. They also have a location in the park. The carriage paths are great for an easy walk or bike ride. Echo Lake has a nice swimming beach. Reel Pizza is kind of a fun movie theatre/pizza place. Comfy sofas instead of theatre seats.

Visit the "quiet side" of the Island. The Indian Point Blagden Preserve is a Nature Conservancy property that has a nice walk that ends on the shore. It's a very quiet trail. You can either walk on a woods path or along a paved road to get to the shore. It's near the Atlantic Brewing company that also has a barbeque restaurant that serves decent pork barbeque. The beer is good and they also make their own blueberry soda.

I am less enamored with the Jordan Pond House. The view of Jordan Pond is lovely from the lawn, but it's always busy and I think the popovers are overpriced. Definitely think about using the Island Explorer if you decide to go to Jordan Pond.

Acadia is wonderful! Some suggestions:

• Jordan's Restaurant is great for breakfast and opens early, so it's a great place to dine after seeing the sunrise from Cadillac Mountain.

• Check online to see when cruise ships will be in Bar Harbor, as those would be good to avoid Main Street.

• The blueberry soft serve at CJ's Big Dipper is terrific :)

• The sunset nature cruise on the harbor is a nice way to end the day. It gets chilly on the boat, but they supply blankets.

• If you go to Jordan Pond Inn at around 3pm (basically, between lunch and dinner times), the wait will be much shorter.

• Asticou Azalea Garden, which is on the other side of Mount Desert Island, is a lovely Japanese-style botanical garden. If you go later in the day, you may have the place to yourself, which is a nice contrast to the crowds in the park. Enjoy!

We spent a week in Bar Harbor/Acadia in the fall some years ago and had a great time! Hiked Dorr (from Abbe Museum's Sieur du Monts Spring trailhead), Penobscot, Sargent and Pemetic mountains plus some of the carriage roads and some other trails, generally explored Mt Desert Island, and drove over to Blue Hill and Castine one day.

One fun thing we did the day after overextending ourselves (!!) on the summit trails was a drive over to Northeast Harbor and a ride on the Beal and Bunker mailboat to Little Cranberry Island/Islesford. The island is small and doesn't take long to walk around but has an interesting history, and we enjoyed a peek at how the islanders live, learn (at a little K-8 school) and make their own fun (lots of it!) in their somewhat isolated location. Visit the NPS historical museum and maybe have dinner or brunch at Islesford Dock Restaurant (open seasonally)? You can do Great Cranberry via the same boat circuit as well. Some helpful links:

http://www.cranberryisles.com/ferry_b_and_b.html
http://cranberryisles.com
https://www.islesforddock.com
https://acadiamagic.com/Islesford.html
http://islesford.com
https://acadiamagic.com/great-cranberry-island.html
http://www.cranberryschools.org/home

While some have turned over, I'm pleased to see others of the restaurants we enjoyed still going strong: McKays, West Street Cafe (see their early-bird specials) and Thurston's. Skip Stewmans: was a reco from a local and thought it was overrated.

For post-hike brews/libations: The Dog and Pony Tavern. It was called something else when we were there but looks to still be a local fave. They have a big outdoor deck for kicking back with a cold one and has food too. It's off the main drag, which is nice as day-trippers aren't as apt to find it.

When the tide is out, walk the gravel bar from downtown Bar Harbor to Little Bar Island: just have a tide table so you know when the tide is coming IN again. :O)

Getting around: yep, use the Island Explorer for most-visited spots, like Thunder Hole and Jordon Pond House (nope, not a fan either as it's just too darn busy). Park Loop Road - especially the long one-way section - is very slow and congested, and the big tour buses can be a pain to get stuck behind. We did some of that early in the AM with our own vehicle (another option) for scenic spots and to access some trailhead parking before it got nuts. The NSP website will be a great help for maps and trail info:

https://www.nps.gov/acad/index.htm

Editing to add: if you're into history, Castine is old and interesting!
https://www.castinehistoricalsociety.org

Get out of town & over to the Schoodic Peninsula part of Acadia. WAY less crowded, gorgeous scenery, infinity of quiet rocks&surf places to make your own, small real communities. Google town names for details. Great for biking.

Or, if that's too far, on Mount Desert Island get down to its southern ends. Bar Harbor's the anomaly of Acadia; good for fd&lodging choices, bad, bad, bad for crowds & commercial-ness. The Abbe Museum's good.

The island ferries, to the Cranberry's, etc., also recommended.

A couple of warnings-June can still be chilly, especially at night. It is also the height of mosquito and blackfly season. Be prepared as you move even a little bit inland.

I second the recommendation for Schoodic. It's part of the national park but far less visited. It's worth the drive. There are fairly new bike trails but they move inland. The road is your best option for traveling close to the water.

Campebello, FDR's summer home is interesting and also a beautiful spot. Remember it's in Atlantic Canada, so the time is one hour ahead of EDT. The drive goes through truly rural coastal Maine. There's not much left anymore, so enjoy it.

I got two words for you: Lobster Rolls.

Mmmmm...

@Kim - thanks for the tips about flies and mosquitoes - I never would have thought that for June!

I'll let y'all know what we decide to do...have not had much vacay planning time lately due to work (how DARE work interfere with my travelling, hahaha.)