Bringing your own saddle is excellent advice. I recently did bike test rides and I was so sore after riding all of the other saddles, most felt like they were hard as rocks.

Just ride everything that you can in the general price range that you can afford, even a couple out of your range just so you can compare the difference. Some bikes you can rule out right away but when you get on one that you like you will know it. I had 2 bikes that I ended up really liking out of about 8 that I tried. I went back to both shops and took each bike out for another ride and finally decided on a Giant FCR 3w.