Four Nights and Five days in Iceland

You are right, that is wayyyyy too much for the day of arrival. Take that first day and stay in Reykjavik, as that will give you all day there and by walking around in the fresh air it will help with jet lag, then early to bed and by the morning you will be raring to go. Then that second day head up to Westmann Island. I would spend all day there, possibly even the night, and then the first ferry back in the morning. The reason I say to stay over is the puffins are on land early in the morning and late at night, so that would give you opportunities to see then vs mid day when they are just flying around. Plus the rub boat safari is a lot of fun there, and then Eldfell crater to hike up and the museum at the base of it (not to be missed), etc. I would Then head further up the coast to around Jokulsarlon and stay in that general area. Do the zodiac boat ride there and then go across to Diamond Beach. Stay the night somewhere along this south coast area. Then wander back down and stay the night somewhere around Selfoss or the Golden Circle. That is still close enough to the airport for your last day, and you will still have time to see stuff along the way.

Whatever you choose, you better hurry to make lodging reservations as most places book about a year in advance. I would also get a rental car reserved. We always use Blue Rental Car and have always had good experiences with them. We do opt for the full insurance instead of using our credit card insurance as this covers more, and I don't want to pay first and then deal with reimbursement etc later. I just want to be insured and not have to worry if anything happens.

Where are you flying from? Do you know how you fare with jet lag and know that you'll all be fully functional on arrival? I had a similar arrival time and I was absolutely beat on my first day, and know I wouldn't have done well driving as far as you suggest (or driving at all). As mikeliz97 noted, that first day is ambitious and their suggested itinerary is reasonable. But there is also nothing wrong with your original plan of doing day trips either (that is what I did on a five night trip but in October). Note it's a solid 45 minute drive from central Reykjavik to the airport, so if you decide to stay in the city on your night before departure, make sure you give yourself enough time to get back, return the rental car, get checked in and through security to your flight. And I agree you should make reservations asap, even for day tours, as June is very busy.

Thanks for the advice. We are fairly experienced travelers, and the flight is from NY area, so it is only about 4 1/2 hours. Thanks to your feedback I am thinking a revised itinerary :
June 1: arrive at 5 AM, and directly do the Golden Circle. Then try to get to Vic for first night
June 2: head up the south coast to Jokulsarlon glacial lake and the diamond beach, spend the night up there
June 3: drive back to Westman Island ferry, spend evening on the island. My only concern is that Google maps currently shows the road closed (route 1) between Hofn and the Ferry, (could that be a winter thing? or the Volcano?)
June 4: drive to Reykjavik and spend our final day exploring the city, maybe the blue Lagoon too? (Is there an alternative hot spring less touristy- or is the Blue lagoon a must see?)
June 5th: leave for Airport at 12 noon

We are OK with hitting the ground running. I like the fact we can relax out final day knowing we are just 45 minutes from airport. Thanks again!

I really urge you to rethink that arrival day. Going all the way to Vik is too far. I say this because I am keenly aware of what falling asleep at the wheel can do to you. My aunt became a paraplegic from that exact thing. I know we all think that won't happen to us, but trust me, if you do that and only hurt yourself, you are lucky. But imagine hurting or killing someone else on the road with you. We too like to hit the ground running on trips, but know that in a vehicle it is very different than walking around a city with the fresh air to keep you awake. In the car, you don't realize you are sleepy until it is too late. So please seriously reconsider that arrival day. You can still do all that you want, but in a safer manner just by changing what you do what days.

You will want to be back at KEF no later than 12:30, and allow an hour from KEF so that you can return the car, so that means leaving Reykjavik at 11:30 that day. We have done this numerous times so know the routine all too well.

Winnm, I agree with mikliz. Think about the day that you fly to Iceland and how much sleep you'll get before getting on the plane. And then your flight is only 4-1/2 hours, so maybe you'll get 3 hours of sleep? And then you plan to hit the ground running and drive all day around the Golden Circle and all the way to Vik? At least cut down some of the driving and stay somewhere like Selfoss or someplace closer to the Golden Circle. Even better, spend your first day in Reykjavik and then head out on your second day and follow your revised schedule from there (moving day 1 to day 2, etc.)

Ok, we will do Golden Circle and stay in Selfoss the first night. thanks. I feel like this vacation is going to be a lot of time in the car, looks like over a four hour drive up to the glacial lake in Jokulsarlon . That might be too much, Is there other stuff to see maybe just two hours drive up the southern coast?(Because we have to drive back down again) I am thinking third night on Westman Island. Fourth night in Reykjavik. We have just four nights total.
Appreciate all your guidance.