This thread was interesting for me. I thought it was my weight loss causing problems when sitting..maybe it is the fibro. Park benches, forget it, I just can't sit on them for more than 5 minutes without pain. If I sit too long, my gluteus muscles react, even swell, then goes into sciatica. I can't imagine sitting on bleachers any more and I used to nearly live on them with 5 kids!!!
I bought a 4" thin memory foam mattress at Walmart, best deal anywhere, and it's a life saver. I have had it for maybe 2 yrs and it's still great. I can't imagine not having it.