We stayed at the Ice Hotel this Spring! It was cold! If you stay there for more than one night, you can stay in little cottages. You don’t stay in an ice room more than one time!
They give you a sleeping bag for the night and the bed is covered with reindeer pelts so it is not too bad (unless you have to get up during the night to pee).
During the time when you are not in the room, you can do reindeer sled ride or racing. Also dog sledding to see the Aurora Borealis.
We also took in a hockey game in Kiruna and went skiing at Riksgroenson, about 200 Miles north of Arctic Circle.
It was a fun vacation, tho it would have been better in Dec-Jan when it is near 24 hours darkness.