Funny, I still do fine sitting on the ground with my back against a log or my pack. Sleeping, though, is another story. Here's my sleeping pad history (those who have already seen it can skip this!). In each case, the change was motivated by hip/shoulder pain when sleeping on my side. It seemed as though my pads were getting thinner and thinner, but it was just me getting older and older!

Teen years--nothing or a blanket
20's, 30's, early 40's--blue foam pad or uninsulated air pad (latter when car-camping)
mid-40's to mid-50's--standard Thermarest (their earliest version)
mid-50's to mid-60's--Thermarest LE, 2 inches thick and almost 2 lbs.
Late 60's to 74--POE Insulmat Max Thermo, insulated air pad, 2.5" thick. 17 oz.
Current--custom insulated air pad from the late lamented Kooka Bay, 3.5" thick, 13 oz.

With the insulated air pad, I keep it really squishy, so my hip and shoulder are almost to but not quite touching the ground. This keeps my spine parallel to the ground when I'm on my side, increasingly important as I get older.

Between the last two I tried a Thermarest NeoAir and just couldn't get comfortable on the horizontal baffles. Every time I got near the edge I would roll off, and I couldn't get the perfect inflation described in the preceding paragraph. It appears that everyone who has tried this pad either loves it or hates it--no middle ground here!