I carry pretty light. I am a warm sleeper and use a Big Agnes Yampa +40 bag. I also use the Big Agnes inflatable sleep pad. With Big Agnes bags the pad slides into a sleeve in the bottom of the bag for two reasons, 1) you don't slide off the pad, 2) there is less loft put into the bottom of the bag to save weight.

If its colder than 40F then I put on more layers of clothes but like I said I am a warm sleeper. I could sleep in long johns, bacalava and wool socks in that bag and be warm to 20F.

In summers with temps guaranteed over 50F I just carry my inflatable a closed cell foam mattress and my 'woobie' (military poncho)