I use one of these during the summer http://www.ebay.co.uk/itm/THERMARES...s_SleepingMats_Airbeds_CA&hash=item4d095c3fd7
I really like it as it's not restrictive like a normal bag, has foot to slip over your kip mat and is very toastie!! for colder weather you can buy self adhesive press studs to fix on to the kip mat and hold it in place. Although I've never felt the need !! great pack size and weight
I've been using Mats' summer top quilt, or a PHD Minim 300