I want to get back into bicycling after a long, l-o-n-g absence. Where do I start?

I no longer know anything about the varieties of bikes available. I do know I want to do very little off-roading, if any, since there is a bike-trail by my house and lots of country roads to ride on. I'm in my early 50s, out of bike shape and I know I need a nice cushy seat because the last bike I rode on felt like the seat was a razor blade. (Ouch. Is it possible that kids don't feel that pain?? Cripes. I wasn't sure there was a seat on there after a few minutes.)

Does anyone know of any good bike shops in west central Indiana? I'm about halfway between Terre Haute and Indianapolis. Also, any recommendations for beginner bikes and seats will be greatly appreciated. I suppose I don't want a mountain bike but what kind DO I want?

Thanks!