If you have a resort nearby that has trails there are usually bikes for rent. For example I am going to Mammoth Lakes tomorrow, and they rent bikes. That's one way to test ride. Or get to know women who ride and if they're your size they might take you out on a test run. Fit is not as critical on a mtb.

I ride a hardtail but feel I need a full sus for the same reasons as tomgrrl. I rode an 8 mile technical downhill today and was up in the pedals with my butt behind the seat almost the whole way. My arms were history and my hands numb. You take a lot of abuse on a hardtail. We shuttled the bikes back up and I volunteered to drive down and meet the girls after their second run.

You will probably want an "All Mountain" bike as opposed to XC or Freeride. I tested a Trek Fuel as I posted before (too short in the top tube). I also tested a Gary Fisher Cake 2GS which I liked because it comes in a size 13". My friends ride everything- Specialized, Cannondale, Santa Cruz. They are all taller than me so I can't try theirs. And everyone loves their Full Sus and hydrallics. Have fun shopping, and buy the best you can afford, even if it means waiting (that what my Dad always said.)