If you buy directly from Tempur they offer the 60 day trial but the Tempur mattresses are the most expensive and Tempur Direct may not be the cheapest place to buy them. The other thing to think about is delivery. We bought ours (Tempur) from the cheapest place we could find online but the delivery was only inside the front door and not up to the bedroom...At the time it wasn't a problem but its worth thinking about, especially if you are going for a bigger nattress as they weigh a ton.
The first mattress I bought had a fault....it went sideways.....the shop had a sense of humour....
They sent the new lad to inspect and question the buyer about the "wear and tear" the mattress had had.
He was about twelveish....and had to ask this ancient, widowed pensioner about the number, size and weight of the people in the bed and what they could have been doing to make the mattress go squiffy.....
I can't bear being hot, so was put off buying a memory foam mattress. I instead bought a memory foam topper, it's about 2 inches thick and just goes on top of existing mattress. I find it really comfortable and it does not make me hot.
Good and bad reports about them. Obviously VERY comfortable BUT they get very hot and very UNcomfortable especially in the summer months. Try a memory foam mattress topper for starters and see how you get on with that. IF, you like it, then invest in a mattress.