Yes, spinning is awesome! I think it might be one of those things you either love or hate, but once you get into it and used to the seat and stuff, it's really fun. I actually look forward to going to class on Mondays and Wednesdays, so I second what JMC said about being more likely to go to a class at a set time than just making a vague commitment to go to the gym. I also really like the people in my class, so it's a good way to unwind and socialize after work. I also have great instructors, but I've had some bad ones too and those guys you do just want to punch in the face lol. Shop around for classes and find one with an instructor you like.
I would also recommend getting padded shorts, and start slow. When your butt starts to get too sore, you can stand up and pedal out of the saddle for a bit. Keep the resistance light--no one but you knows how hard you are working

Spinning definitely did nice things for my butt, legs, and actually my triceps too.