http://www.whatsthebest-mattress.com/ - While this forum may not necessarily simplify your search, the people that post there are very experienced and knowledgeable about everything mattresses! You'll find a lot of invaluable info on the variety of mattresses out there (and there are LOTS of them!)...
http://www.philly.com/mld/philly/living/home/design/ask_expert_front.htm - This is Pete Cancelli's Q&A forum. He is very biased towards Sealy and Stearns&Foster, but there is a lot of good info on mattresses in general here too, particularly in regards to what type mattress best suites what personal sleeping issues.
It is definitely overwhelming trying to decide what mattress is your best option. Based on what you're describing, you're having problems with pressure points. Hip pressure in side sleeping women is a very common complaint, especially with firm mattresses. Something that may help you out in the short term (until you find that right mattress set) would be a 2-3 inch soft (14 or 19 ILD) latex topper or a "memory foam" topper for your current mattress. You can order them online or buy them at most specialty bedding stores. I have the same problem with pressure points at the hip and shoulders that's been relieved by a 1.5 inch memory foam topper under a soft quilted mattress cover.
I agree with what Unblock said above. Make sure that you buy from a retailer who has a well defined return policy. Most will offer a "comfort guarantee", where you have anywhere from 30-90 days within which you can return the mattress for either an exchange or money return. If the retailer seems in the least bit evasive about their return policy, walk away and go elsewhere. Also, check out your local Better Business Bureau for retailers with a good history of customer service. Mattress retailers are one of the most commonly complained about specialty retailers.
Hope this helps, and good luck finding a good night's sleep!