REI Co-op - Siesta Hooded 20 Double Sleeping Bag

The double Exped Megamat is awesome. I've zipped two rectangular Kelty bags together and that worked fine. Upgraded to the REI Siesta 20 double bag and quite like the pillow garage and adjustability. I usually have an additional blanket or two on top because I run pretty cold.

https://www.rei.com/product/245459/rei-co-op-siesta-hooded-20-double-sleeping-bag Went with this in the 30°version and have a Chinese diesel heater & no complaints at all

You don't mention what rating you're looking for... I've been very pleased with my REI Siesta Hooded 20f bag. I used it, along with a REI R7 sleeping pad down to 25f and stayed very warm and comfortable. Getting out of the bag at 25F sucked though. That bag comes in regular and long, the hood making it VERY nice while still in a rectangular form factor.

It is fairly versatile with the zipper design. I've mainly used it between temps of 35f-50f but when it was in the warmer of those temps, there is a full zipper on the left side to open the entire bag up or you can unzip the foot box area by itself. Additionally, there is a 1/2 zip on the right side so the bag over your chest area can be folded down. I usually just sleep on top of the bag with a light blanket when too warm.