If you're looking for firm, breathable, and long-lasting, have you looked at natural latex mattresses? I got mine from Ikea. Coupled with a bed frame that has slats, we can customize the level and location of support (my side/her side; shoulders/hips/legs). I like it a lot. I sleep really (really) hot, so a breathable mattress was the most important thing for me. I find the memory foam stuff too hot.That's gold. It's the first coil bed that's not super expensive that we've come across. Thanks.