Went in November, Blue Lagoon was shut and went to the Sky lagoon which was good.
If you want to do another lagoon then book a Golden Circle tour that includes the Secret Lagoon, not as plush as Sky/Blue lagoons but still nice
Booked all trips and airport transfers through Reykavik Excursions. All were easy and hassle free
We found a few bars that did a happy hour in the afternoons which made things a little bit cheaper. Lebowski Bar had a Burger, chips and pint offer which was pretty good was also showing Iceland getting beaten by someone in Euro qualifying when we were there so they may show more games.
My biggest bit of advice is pack a hip flask and pick up a bottle of something in duty free.
Loved our trip but not cheap