You have probably noticed before how much I have extolled the virtues of Thermarest’s wonderful sleeping pads. I particularly adore this one (the Noeair XLite Womens) as it as light as a feather (340 grams), ‘fits’ me perfectly at 20” x 66” (51 x 168 cm) and is superbly comfortable (moreso I think than my own bed) at 2.5” thick (6.3 cm) and warm enough to sleep on a block of ice (I have) with an R-rating of 3.9! https://www.thermarest.com/mattresses/womens-neoair-xlite
You will probably have glimpsed this little piece of yellow in many of my hiking photos, often folded up into a chair, eg here: http://www.theultralighthiker.com/the-last-of-the-mountain-men/
I am about 5’8” so my heels just hang over the edge, and the rest of my body fits its mummy shape just about perfectly – which is what you want to make an inflatable pad super-comfy. I also think the horizontal tubes have an edge comfort wise over longitudinal ones but this may well be a subjective thing.
The first point is the most important one anyway: If you have surplus mat at the ends, sides or corners your weight will drive the air there and you will sink further into the mat. This means that the mat has to be inflated more to support your weight from sinking to the ground (usually your buttocks or hips) at the heaviest point.
To me a tightly inflated mat is less comfortable than one that is less so. I prefer a softer bed. I realise this may not be so for everyone, just most people, but if you are like me you will want to chose a mummy shaped pad and cut it to just 2” shorter than your actual height (as I explain how to do here: http://www.theultralighthiker.com/modifyingshortening-hiking-mats/) so that it is both exquisitely comfortable and the minimum weight!
If you are a bit wider than the pad lying on your back (I am) then your arms will want to hang over the edges. When your elbows sink down onto that block of ice they will get cold unless you employ some side insulation. A couple of pieces of closed cell foam placed alongside the edges of the mat work just fine for this. I have found the Gossamer Gear Sitlight pad split in two is just perfect for this, and just perfect for side insulation in a hammock too. See: http://www.theultralighthiker.com/side-insulation/
From Thermarest’s page:
The women’s NeoAir XLite mattress delivers more warmth and comfort per ounce than any other three-season air mattress available. Cold sleepers will appreciate our Women’s version, featuring an added layer of our reflective ThermaCapture™ technology for added warmth. New softer fabrics bring better next-to-skin comfort and boost in durability with no added weight. For the discerning alpinist, thru-hiker or backcountry minimalist who’s counting every ounce, there is simply no better choice to assure the kind of rest you need to get done what you’ve got planned for tomorrow. Stuff sack and repair kit included.
Ultralight: Advanced fabrics and a tapered design make this the lightest 3-season backpacking air mattresses available, with no peer in its warmth-to-weight ratio.
Warm: Multiple ThermaCapture™ layers trap extra radiant heat for cold sleepers, without the bulk, weight or durability issues of down and synthetic fills.
Comfortable: 2.5” (6 cm)-thickness, soft-touch fabrics and baffled Triangular Core Matrix™ structure provide unrivaled stability and support.
Ultra-Packable: Low-bulk materials make the XLite mattress the most compact NeoAir mattress ever – as packable as a water bottle.’
PS: Repairs: Though they are quite tough you will inevitably manage to puncture your pad. Mine was punctured within a day of my having bought it by a certain puppy (you will have met Spot if you have been here before) grabbing it in his needle teeth and dragging it backwards out the dog door onto the front lawn where he engaged in a full-blown mock battle with it until I intervened. I have found that nothing beats cuben tape (http://www.theultralighthiker.com/cuben-tape/) for patching holes in them, The cure is instantaneous, efficacious and has not had to be repeated (Spot is now four years old). This tape is also excellent for a wide range of other repairs (raincoats, tents etc) and should always be carried!
PPS: Thermarest also have a chair which will do this but I own the Big Agnes Cyclone Chair ( I think slightly lighter) which has served me as furniture for many years in many wild places: http://www.theultralighthiker.com/cyclone-chair/
PPPS: Another feature of inflatable mats is that you can get yourself and your pack (dry) across swollen rivers relatively safely with them by using them as a kick board. I have had to do this numerous times. Usually it is winter, so it’s not much fun, but if you need to cross…I usually take all my clothes and my shoes off first and put them inside my pack liner.
PPPPS:The RRP for this pad is US$159.95 if you buy it from the States and use (eg) Shipito (https://www.shipito.com/en/?id_affiliate=5249&countrycode=AU) to get it to Oz (Recommended).