I am 6'1" 250 and am a slide sleeper who tosses about a bit in the night. I have a Klymit Static V Lux Insulated pad at 35oz (30"Wide x 76"L x 3" thick). I really like the elbow support when on my back and the added width is really nice for my arms when on my side.
They have new, lighter version that is 31.32oz (27"x78"x3.5")
I have found running a Nemo Switchback (14.5oz) foam pad (72x20x0.9) under is not only warmer on colder nights but also is a bit more comfortable on my side so I can run the air pad less firm for better contouring of my lower back. On nights below freezing I wrap an emergency blanket (2.5oz) over the air pad for more reflection. This makes the system almost as warm as running the reflective foam on top of the air pad but much more comfortable. You could shave some weight ?(4oz) going to the shorter version (51"x20"x0.9") but I figured I can always cut a couple panels off the longer foam pad for a seat cushion if I really wanted. I chose the Nemo because it is thicker than the Thermarest foam pads.
As I bigger guy, I had a heck of time finding a bag that fit my size and fish out of water style of sleeping. I looked hard at the Big Agnes Bags but found them to be a bit heavy considering they are basically quilts due to the lack on insuation on the bag with their ingenious sleeping pad pocket. Unfortunately that pocket doesn't fit wider or extra thick pads. I like the comfort of a quilt for my style of sleeping but wanted to be able to zip up if needed on colder nights. I came across the SeaToSummit Explore Down 25* bag (42.5oz).

It has adjustable and replaceable straps on the bottom to secure to a pad that work great even on my larger pad. These strap are also on the lower half of the bag so you can sit up in the bag and stap warm which did not seem to be an option in the Big Agnes design.
The STS Explore also has a double triple zipper so both left and right sides can be vented as well as the footbox. This makes it really nice for controlling temp in different conditions. I have tested it in mid 20's and it is true to temp or better if you have the right amount of insulation in under you in the pad system. I sleep warm and was too hot @ 22* with the Nemo foam pad on top of the Klymit pad. Switching the foam under the air pad, I froze as the air in the pad cooled and sucked the heat out of me. Adding the emergency blanket solves this nicely. I have not tested this bag yet in temps warmer than high 50* buy was still very comfortable. When it gets warmer I will switch it over to quilt mode. This bad has the option to unzip the top 2/3 form the back panel and use it as a quilt. Very cool way to convert and drop some weight. Needless to say this bag has tons of room to sleep comfortably. the small details like the inside pocket for water filter/batteries (small but usable) and the draft baffles make it a very nice bag. I ordered the long and have plenty of length to stick cloths at the bottom in colder temps. There are synthetic versions and colder version for those interested.
It all fits nicely in my Seek Outside Cimarron w/ Nest
Most of the stuff I found when looking for my system seemed to be designed for someone wearing skinny jeans, so hope this might me helpful for those looking for a more comfortable night tossing around in the back country.