I have an old innerspring mattress that is firm underneath but soft on top--one of the older versions of a pillow top. My mom also has an innerspring mattress but one of the newer thicker versions of the pillow tops. If you have a lot of muscle aches hers feels better than mine for that.
The company we purchased from is mostly local, I think. They allow adjustments for one month afterward and then for the life of the mattress but it cost more for the adjustments later on--like $60 pick up and deliver fee or something like that.
We also purchased a well known name brand innerspring mattress years ago from a furniture store. Little me could carry that with one hand. I didn't try that in the store but it made me realize later on that there wasn't too much support inside if it was that light. That one, even though it was a pillow top was bad for both my mom and me. I tried it and then she offered to try it. Unfortunately, their return policy on mattresses was "no returns allowed." I didn't see that when I bought it. (I should never have gone shopping after working a full day in the office.)
I'm saying all that to say if you are shopping for a mattress I think it would be better to buy from a company that makes their own mattresses and also offers future adjustments or at least free returns in case it turns out to be a bad purchase for you.
I don't know about the new memory foam mattresses but just laying on one in the store made me itch like crazy because of my MCS (multiple chemical sensitivities), even through my clothing. (Just another consideration.)
Hope some of this helps.