Hi Sarah, I've been cycling for years and currently do spin 4-5 days a week, plus upper body workouts to keep myself evened out. I think it's the best stress reliever there is (well, for me).
However, you should consider buying a gel seat cover if you want to continue cycling regularly. Aside from it being easier on your bottom, it's all yours! I've seen too many people get off the bike without even a simple wipe of the saddle.
Considering how much a person can perspire during a one hour class, it's just more hygienic to use your own cover.
Another thing to consider if you plan on keeping this up long term, is to invest in a pair of cycling shoes where you can clip into the pedals. You'll feel a greater difference in how that will work your hamstrings.
Keep riding!
Anya