May Trip

My honeymoon was spent in Croatia, so I love these kinds of questions! We had two weeks, and we somewhat regretted moving too fast, but we've been back three times since.
Looks pretty good, though I see no need for the car until you leave Split. It will be more efficient to use bus and catamarans.
I'd probably cut Zadar in favor of an overnight on an island, and choose Plitvice OR Krka, not both.

Look at šibenik in place of Zadar.

I personally don't think it would be more efficient to use catamarans and/or buses to travel from Dubrovnik to Split because you are then dependent on their schedules. Driving in Croatia is very easy, and the drive from Dubrovnik to Split in particular is easy. You do not need a car in Dubrovnik so pick up your car when you leave Dubrovnik. That is what we did.

The day trip to Hvar is very easy from Split. We took the Jadrolinija catamaran. Takes one hour. Hvar Town has a party reputation but it was not like that at all when we were there in September 2019. May is not high season so I don't think Hvar Town will be party central then either. I loved Hvar. Hvar harbor is beautiful; the hike to the fortress is rewarding with stunning views of the harbor, red roofs, and the Adriatic! We took a very scenic coastal walk starting from near the harbor. Haven't been to Brac so can't give any advice. I think you should make your decision based on how long it takes to get there.

I haven't been to Zadar so can't give any advice. But I know my daughter and son-in-law really like Zadar.

While in Split, I highly recommend hiring Maja Benzon, recommended by Rick, for a 2-hour guided tour of Old Town and Diocletian's Palace. You will appreciate Split and the palace more.

Are you planning on spending any time in Split itself? It looks as if you will simply base in Split. There is the actual palace. There is also an Archeological Museum. There are the Roman ruins just out of town. You may want to spend some time there instead of immediately leaving for other places.

I would drop the drive to Zadar. Instead, go to Zagreb for 1 extra night. There's a little uncertainty in Zagreb, as many museums and such were closed by the earthquake of 1 year ago. Still, more to see there than in Zadar, and you already have gone to Trogir.

Re the car, I’m all for driving when there is time for meandering, exploring, but just to drive to Split and park the car for two full days seems a waste.
But I do heartily agree with kmkwoo on Hvar, it should be lovely in May (I’d avoid in August).

Yes, many museums in Zagreb are closed. The ones in the upper town are open, but St Marks Church is closed for repairs as is the cathedral. The ethnographic museum in lower town is open and it is lovely. The also opened a Chocolate Museum recently which was fun.

If you are going to Plitvice there is no need to go to Krka too or Zadar.

On Lokrum if you wander around you will see a few GofT sights. When we were there in 2018 they had a small museum with screens showing interviews and the scenes shot on Lokrum. They even had a sword throne you could take pictures sitting on. We were literally the only people there.

I also have a great guide for Split, he can incorporate GofT sights. His name is Pero Ugarković and his email is lignja@gmail.com. We use him every time we visit Split.

Thanks everyone for your input! We have decided to cut out Zadar, we will just have to incorporate it in a future trip when we do the northern peninsula.

I think we've decided on 2 nights in Dubrovnik, driving to Split, spending 1.5 days in Split itself (4 nights total) with a day trip to Hvar, and a separate day trip to Brac (she really wants one full beach, Golden Horn looks great). Does anyone know how to go about getting a ferry ticket to these islands from Split? We would love to take the $5-10 ferry over the $100 Trip advisor group tours.

We are still going to Trogir and Krka on the 6th day (she wants to swim in a waterfall) and then to Plitvice for that evening and the following morning, then driving to Zagreb. We will get about half a day to explore Zagreb which I know isn't a lot for a capital city however Zagreb for us is more of a destination for the airport to get us home. We will visit again to enjoy Zagreb in the future when hopefully we include the northern peninsula and Slovenia!

Good call--that extra day will make a difference! Zagreb is the easy to fly through, so you'll be back.

Krilo catamarans: https://www.krilo.hr/en/sailing-schedule/
Jadrolinija catamarans: https://www.jadrolinija.hr/en/sailing-schedule/local-lines-2023

Brac's zlatni rat beach (aka golden horn) at Bol is probably a good choice because the sea is still cold in May, but there is some shallow water there, and you just might feel like it is warm enough for a swim.

Kris and I are also active travelers, avid hikers, etc. We did our first trip to Croatia last summer for ten days. From what you've laid out, I agree on skipping the car rental in Dubrovnik. Just take the ferry to Korcula and/or Hvar/Brac, spend a couple of nights there, then ferry to Split and pick up the car the morning you leave. We spent a night in Sibenik, wonderfull old city there, and a night just outside Plitvice in a comfy air bnb, which was the ideal way to do it in the busy season. Get there before dark, then up early to enjoy the lakes before they get too crowded. We arrived in Croatia from Venice via train and bus, rented a car in Rovinj and dropped it off in Split. So we missed Zagreb. As for Lokrum, we spent maybe three hours there and found that sufficient. It's a quick boat ride over.

Do a double check - but if you are planning to swim at Krka, I am not sure that is possible any longer.

Imo I’d rather spend a night on Hvar and see some of its amazing beaches than do both Krka and Plitvice