Hi @rookiemere. It was a fantastic trip and long awaited. I'd been wanting to go for 30 years!
In Reykjavik we stayed in Old Charm Reykjavik Apartments. They have 2 and 3 bedroom apartments and are a couple of minutes walk from Hallgrimskirkja (and have parking). In Vik we stayed in Vik Apartments owned by Hotel Vik. Very modern and glossy with a view out to sea.
In both places we made packed lunches and ate in some nights to save ££. I liked Kronan supermarket as it is a bit like Sainsbury's.
Our last night was at the Northern Light Inn (all in 1 room) very close to the Blue Lagoon (and a power station which was a shock!). We used Blue Car Rental as recommended by Trip Advisor!
Only our 2 late teen DC did the snorkeling between continents but we all did the Glacier walk, Lava Tube and boat trip. We used Tröll for snorkeling and Glacier. They were a bit cheaper than other operators and were fabulous. Boat and Lava Tunnel booked on their website.
The drive to Jökulsárlón and back from Vik was very long. Ideally we would have stayed there for a night but I didn't really want too many accommodation changes. Hence 3 nights in Reykjavik, 3 in Vik and 1 in Northern Light Inn.
Top tip is that the weather is a major factor in Iceland so keep plans flexible.
Tröll are very good in that you can cancel up to 24 hours before for a full refund.
Other top tip is to keep an eye on beer prices if you go to the great craft beer place in Vik. I think DH's beer was over £20. Alcohol is very expensive there.
I think we were lucky to get August for April prices but no Northern Lights in early August. Apparently there is a chance for late August.
Costa Rica is on our list for our 25th Anniversary. My DC are now 18 and 22 and have assured me that they will continue to come on family holidays if the destination is interesting and we are paying!