I took a spin class at the gym this morning and the bike is upright which can make you sore in the rear-end area. The recumbant is much more comfortable. If you have a bad back I would think the recumbant would be more comfortable than an upright. Are you going to get a recumbant?
No, they just have both styles of exercise bikes at the gym, and somehow I feel I get a better workout with the regular upright. The seats on the bikes in the cycle classes are super narrow, good recipe for sore rear syndrome.