I also usually fly QR when going east but credit to BAEC.

I'm quite happy with a 2-3 hr layover as by the time I've had a cigarette, stretched my legs, had another cigarette, something to eat and drink, and a final cigarette that's a couple of hours and I'm raring to go again

There is an airside hotel if you have a longer layover which (from memory) rents rooms by 4 hr blocks - I once got a room for 8 hrs when I had a 10-11 hr layover. They also offer free tours of Doha if you have a long layover at certain times of the day but I've not sampled that yet.