24 hours in Reykjavik

I would find accommodations either close to the Reykjavik bus station or in the town center. I would suggest a walk along the waterfront and pop into Harpa. I'd go to the church Hallgrimskirkja and take the elevator to the top of the tower, and I'd do a golden circle tour.

Rick has a great article on this: https://www.ricksteves.com/europe/iceland/itinerary

There are tons of tours (e.g. Viator) that do the Golden Circle and South Coast tours via bus. You could also rent a car for more flexibility.

Also note the Blue Lagoon opens early (7am) and stays open late and it's near the airport so you can do it coming or going from airport.

You can take a bus from the airport to Reykjavik. (https://grayline.is/tours/keflavik-airport/keflavik-airport-to-reykjavik-hotels-8706_76/) It doesn't really matter where in Reykjavik you stay, they will drop you at your hotel. It's about 45 minutes to an hour each way. Staying by the airport would be a mistake, as it's in a very remote location.

A day tour to the Golden Circle would be nice, but unless your flight out is after 8pm or so, it's not going to be possible. These tours run 8 or 9 hours, so you wouldn't get back to Reykjavik until late.

It really depends on what the 24 hour window is. I think you may be better off exploring Reykjavik for whatever time you have, and maybe add a Blue Lagoon stop on the way back to the airport.

EDIT: Rick's 24 hour Iceland Itinerary is fine if you rent a car and if your 24 hours start early in the morning.

Lane, thanks, I misspoke as I typed my fast response on my way out the door. Its a bus station where the bus from Keflavik comes and leaves from. I stayed in town, and yes you can get transportation directly to the hotel, but my observation was like many tours I've been on, it is a lengthy process dropping people at hotels so unless you're among the first to be dropped off, I'd rather get my own transportation or walk. The bus station is also where some of the golden circle tours leave from. My golden circle tour was not 8/9 hours and there were tours leaving in both the morning and early afternoon

There is transportation to and from Blue Lagoon from the airport. I guess it is good to have it as an option if nothing higher on a priority list is open early or late in the day. It's man made, and very pricey. I didn't do it during my week in Icelend. I am curious to hear the opinions of those that have gone. It does appear to be a very novel venue. My son and his wife did a natural hot spring which they did enjoy.

Jules, I removed my note about the absence of a train station.

I based my estimate of the time for a Golden Circle tour on the listings on Viator. There may be some that are shorter. In any case, it all depends on when the 24-hour window starts and ends.

It's also my understanding that you can no longer take buses directly to the hotels in central Reykjavik. There are bus pick-up and drop-off points within walking distance of all the hotels. So it may be easier to book a hotel close to the bus station, but if I only had one day, I would want to be in the center. The time saved in airport drop-off and pick-up may be made up in the time spent walking to points of interest.

Lane, you are probably right on where to stay. I was more on the "fringe" of the "downtown", because that was where I could find a room I felt like paying for. It was a couple blocks from where I'd consider the center of town is. I'm glad to hear that the govt is taking some thoughtful steps to manage their tourism. The tourist buses do not need to be in the center of town. Its been about 4 years since I've been there. Its such a special place, you just hope it can keep its charm.

If flying IcelandAir you can book your Flybee bus ticket from the airport, a hotel, and a tour all as an inclusive package along with your flight.

We are booking our trip—-haven’t been there yet. I’m suggesting this based upon recommendation of a friend who recently did this booking.
When we researched this way of booking directly through IcelandAir we found prices to be one third cheaper than booking these travel events individually.

Good luck and let us know how you do!