Thermarest or cheap copies from decathalon. Comfy and warm.

Vango 7.5cm double self-inflator (Vango Comfort 75)

Warmer, firmer, easily adjustable to required inflation. Packs large so car-camping only, but I slept on the single version as my main bed for a number of years and actually prefer it to a sprung mattress.

A little spendy compared to air mattresses but good sleep is worth it.

I've got a 10cm Gelert s/a mattress, picked it up cheap as they seem to be discontinued now. First time I've used one, previously used one of those big inflatable mattress things, which was horrid, and was cold and wouldn't stay inflated.
The Gelert was very comfy indeed, but the issue was getting the air out! Once it's had extra air put in, opening the valves means nothing actually happens, it needs lots of kneeling on it while rolling it up.
Which is a good thing, there's plenty of scope for adjusting the air to make it softer or firmer.
The 7.5cm Vango sounds like just the ticket, unless you can track down a remaining Gelert somewhere.
Mine has encouraged me to spend a week wild camping in South Devon in September, something I never, ever thought I'd do, at my age! 😀

The fattest thermarest copy. 100x better or campervan mattress. Sometimes used to take the futon one out the spare room too.

Looks like this Vango one is the closest to my Gelert: http://www.amazon.co.uk/Vango-Adventure-X-Large-Inflating-Mattress/dp/B00Q75DBLM/ref=sr_1_1?ie=UTF8&qid=1438644519&sr=8-1&keywords=vango+10cm+self+inflating+mat
I was really lucky, mine was reduced from £60 to £17.50. 😀

Alpkit are doing a double, super thick self inflating sleeping mat. It looks fantastic. Im amazed at how comfy my 3/4 self inflating bike packing mat is so something that big has got to be great. Those old style inflatable mattresses don't work very well.

Hotel room at the Amari?

Old style inflatable mattresses are freezing cold. Thermarests and copies are fantastic as long as they stay inflated.

I'm using outwell 7.5 cm self inflating mattresses which are mighty comfy, warm, stay up overnight (in fact several nights) and have rubberised dots all over the bottom so it doesn't move around. We just butt two against each other for the two of us, which works great and means you're less likely to disturb the other person.

I'm a light sleeper but I sleep great on those.

Any thick self inflator should be loads better than the old school air bed

We use an "old-style" double air bed when car camping and gave fund it plenty warm enough but we do get quite a build-up of condensation between bag and bed. I'm wondering if the self-inflators would reduce this?