I don't know where you are looking at the dog sledding, but I went to one arranged during our stay at the ice hotel, and whilst the time sledding was about an hour I'd guess, the actual time we were there was quite a bit longer (we had a tour of where the dogs live, hot drinks, training on how to guide the sled etc.) I stayed at the ice hotel, and it was amazing, but to just tour wouldn't take very long - just depends if there are any activities you want to do (depending on what they have on). We did some snow shoeing and ice carving when we were there. I'd lean towards giving yourself more time, rather than rushing between things.