This came up in another thread but I thought since it is winter, this might be a useful point of discussion for all of us.
Even though everyone has their own specific needs and ways they go about things, it might raise some interesting ideas some of us may not have thought of or tried.
To keep this more universal, and because it makes more sense, we will keep this to 0 Celsius.
My typical setup is:
If 0 to -5, Mountain Equipment Helium 3.8 SIM, if -5 and below its an Exped Downmat 9, and if on rougher terrain I add a Thermarest Ridgerest solite as well.
Sleeping bag is a Force 10 Altitude 750 down bag (comfort rated to -11). I add a thermolite liner for colder temps, or just a silk liner when hovering between 0 to -5.
I sleep in merino baselayers, unless it gets really cold, then I sleep in my hiking pants and a fleece.
When it is really cold, or my feet feel especially cold, I wear a pair of Rab (Integral Designs) Hot Socks, which are packable primaloft booties.
I would think that for the most part, this is a fairly typical set up.
The downmat 9 is perhaps overkill, but anyone who has slept on one will attest to its incredible comfort! Synmat 9 would be a lighter and more economical option while being just as comfortable, with the only real difference being that it cant go to as low a temperature.
The Hot Socks might be an item most people dont use, but I highly recommend. They pack down to about the size of typical heavyweight wool socks, but are so much warmer (and lighter).