
Exped
MegaMat Series
Car camping comfort champ, but some side sleepers find it thin.

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I use a king size air mattress from Decathlon. It's pretty comfy. But it has no insulation. So when I camp in colder areas I bring along my Therm-a-rest Trail Lite and put it on top. It's all a bit excessive and bulky, but it's comfortable and doable with the rest of my pack. With that said, I'm looking for a better double width, insulated sleeping pad or air mattress that would pack down smaller.
Do the kids really need such a sleeping pad? Why not just some closed cell foam mats (e.g. Nemo Switchback or cheap clone) for them? I also wouldn’t be too sure that the Megamat is a cure-all. The girlfriend and I once had to sleep on some big inflatable guestbed mat thing which was horrible (especially with two people). To this day the most comfortable mat I know for me is the Therm A Rest Trail Lite since it has a flat surface (no ridges), is firm, doesn’t bounce, has a nice textured surface and makes no noises. Even though it’s “only” 3.8cm in thickness.
Thermarest still makes them? I have also seen knockoffs even in non specialty stores. I have an older Thermarest Trail Lite and Trail pro. The only difference to the classic mats is a few cutouts to make them pack smaller. I adore my Trail Pro. Very comfy, good R value, thicker than the traditional pads, packs reasonably small for it's comfort.
Have never needed to use their warranty. My Trail Lite is 10+ years, and is now my loaner pad for random people, or I bring it for my dog, and still in excellent shape. Meanwhile a friend who is neurotic about gear care has gone through 2 of the air pads in that time. I did buy both of mine as clearance items, but maybe take a look at the Trail Scout? It looks like their most classic -and cheapest - version.
I use my full length R4 self-inflating pad all year long. For sub-freezing temps I add a 3/4 length R3.2. I use a 20oz "emergency blanket" (tarp with mylar side) as a ground sheet for bivouac, tent footprint, and emergency shelter.
My first winter camping trip is one I’ll never forget, my back was killing me after trying to sleep on a foam pad. The next trip, I brought a Therm-a-Rest Self-Inflating Pad and it literally changed everything. Suddenly, I was sleeping warm and supported, ready for morning hikes. I’d recommend [air mattresses](https://www.reddit.com/r/KeepThisInMind/comments/1ltzxk1/recommend_the_air_mattress_best_for_camping/) for camping to anyone, from lightweight backpacking pads to thick car-camping mats, especially for winter trips.
I've used a self-inflating Thermarest under a Big Agnes pad...half inflated

Exped
MegaMat Series
Car camping comfort champ, but some side sleepers find it thin.

Exped
Ultra Series
Lightweight side-sleeper comfort, but a bit pricey and bulky.

NEMO
Tensor Series
Ultralight side-sleeper comfort, but slippery and prone to leaks.

Big Agnes
Rapide SL Insulated Sleeping Pad
Comfortable with side rails, but heavy and warmth claims disputed.

Therm-a-Rest
NeoLoft™ Sleeping Pad
Very comfortable, good service, but heavy and bulky for backpacking.

Ranked #1
Exped - MegaMat Series

Ranked #1
Exped - MegaMat Series

Ranked #1
Exped - MegaMat Series

Ranked #1
Exped - MegaMat Series

Ranked #1
Therm-a-Rest - NeoAir Xtherm Series