NEMO - Tempo Women's Synthetic Sleeping Bag 20F Long

I’m a similar build and sleep style and just got a Nemo Tempo 20 Long. I’ve only tried it for one night, but I had plenty of room to roll around.

I have the Nemo Tempo 20 and I LOVE it. It’s so comfy and warm. I just used it on a -10C winter backpacking trip and unfortunately it got a bit wet from snow coming in my tent but I stayed warm inside. Can’t recommend it enough esp since it’s so much comfier than traditional mummy shape.

Look up spoon shaped bags. I have a nemo tempo 20 (which is synthetic) but they have down versions for more money. As a side sleeper it allows enough room to turn over in while also still packing to a compact-ish size.

Depending on your specific needs for temps, weight, and filling I'd recommend, Nemo's Rift, Forte, or Tempo bags. They have a "spoon" shape (extra space around knees and elbows and tapers around the waist and feet) rather than mummy shape. They're designed to feel less restrictive and I've found them to be so. Of course the bag will take up a bit more space than a mummy bag, but it's better than a regular rectangle bag. I have the Tempo and I think it's good for regular backpackers and I really like it. They're common at REI too so you may be able to try it out.

I just got the Trekology UL R7 sleeping pad for my husband and I. Only slept on it one night but it was comfy. I’m a side sleeper. Trying them again Easter weekend so we’ll see. We got the Nemo Tempo bags. For my kids (about the same age as yours), we got the Big Agnes Divide because it fits in a sleeve for their sleeping bags (also Big Agnes) so they don’t roll onto the ground. We did pay more than some other stuff but we went fairly lightweight and compressable in case we try backpacking too.

I just got the Trekology UL R7 sleeping pad for my husband and I. Only slept on it one night but it was comfy. I’m a side sleeper. Trying them again Easter weekend so we’ll see. We got the Nemo Tempo bags. For my kids (about the same age as yours), we got the Big Agnes Divide pad because it fits in a sleeve for their sleeping bags (also Big Agnes) so the kids don’t roll onto the ground. We did pay more than some other stuff but we went fairly lightweight and compressable in case we try backpacking too.

For clarity - The Riff (and Disco) are down. While the Forte and Tempo are synthetic. Their spoon/peanut shape is definitely very popular with side sleepers, or people who sleep angular or toss and turn. Much more forgiving than a regular mummy, without the draft issues of a quilt. Recommend people getting into quilts, to buy a wide one. This will help mitigate drafts. You mention REI, all of their sleeping bags now come in "wide" versions. Still a mummy for the most part, but about 5" wider than a regular mummy. Their Magma is an excellent bag, as is their Magma quilt, but it's only rated to 30 degrees.

Quilts, semi rectangular bags (Sea to Summit Trek and Ascent Down) or the Big Agnes Sidewinder series are what you want. The Nemo Spoon series of down bags are also quite roomy. I sleep on my side. I use Hammock Gear Econ Borrows most of the time and I have a Marmot Col -20F bag for anything 20F and below.

Which 2 in 1 are you referring to? The ones that come to mind would exceed your budget, but examples help.  What temperature are you expecting at night?  Mainly, I would suggest finding an insulated sleeping pad with a stated R-value. Depending on how cold it will be, the R-value changes (higher R for colder temperatures). For sleeping bag, add at least 10°C, so for example, if you expect overnight temperatures around 5°C, find a bag rated for -5°C.  I have a Nemo Quasar insulated pad in the double width (I move a lot), and a Nemo sleeping bag (in their "spoon" style because I can't sleep in a mummy style bag). 

I’m a stomach/side sleeper and love my Zenbivy quilt+sheet and their matching pillow system, but it’s quite an investment for a casual camper. I’d recommend looking for a cheaper quilt or even a rectangular sleeping bag on Amazon or Decathlon if you’re not looking to spend a lot. I was really unhappy with my spoon shaped Nemo sleeping bag. Even though it’s wider than a traditional mummy bag, it was still restrictive. There are a lot of other spendy quilt brands out there and most have already been reviewed on r/ultralight.

I have a cot also but would never sleep on it without a pad when it's cold. I need the insulation. I really like the Nemo spoon shaped bags to be able to move around but why not pile up thick blankets for your first time out before dropping the money on a good bag.