If you want to be comfortable in a wide range of conditions and if you are going to carry it, get a ThermaRest.

I've got 2 standard Therma Rest pads that I bought in late 1982 or early 1983. I converted the valves from the old metal style to the "new" plastic style years ago and patched a pinhole in one about 3-4 years ago (in the field - the kit actually works). They are what we continue to use, many times a year, for both short and long trips, hiking or car camping. Mine has literally been around the world and used in environments ranging from equatorial desert to rain forest to wintertime above the arctic circle; my wife's has been used all over North America. In extreme cold (-40 and below) I find them a little thin for all-night insulation from the ground and in those conditions they benefit enormously from the addition of a 1/4" to 3/8" thick closed cell foam pad (above or below does not matter). FWIW, I think the new models are better than these slick oldies, but I haven't worn these out yet, so...

My second choice has been, and remains, a 3/8" thick full-length ensolite pad - heavier than eva or other light-weight closed cell foams, but more comfortable as far as I am concerned. A couple of my kids lug around 1/2" thick pads, but man, are they ever bulky!

For long term camping in one place in cool to hot weather it is hard to beat a good quality rubberized canvas air mattress. There are a lot of junky ones out there. The only problems I've ever had with air matresses involved foolish pranks with crampons... anyway, we have those and they are fine, but they generally only get used once a year. Too heavy and a PITA to inflate daily; not my preference for carry, although I did for a few years.

Various family members have experimented with the big bulky self-inflating matresses by Slumberjack, Coleman, and Wentzle in various climates and conditions. My wife likes one of them as long as she doesn't have to carry it more than 500m (Slumberjack, I think, but maybe one of the others). None of the rest of us care for those things, but YMMV.

You could also get a couple of inexpensive closed-cell foam pads and stack them atop each other for this trip - a couple of 3/8" pads like surplus US military ones are cheap, versitile, and will do the job for certain, plus you can use just one when you have to pack everything along with you.

But I'll stick with my ThermaRest.

Tom