I like the Kifaru tarps myself better than the flat ones for a sleeping shelter. I've spent many nights in the Paratarp before getting the Megatarp, I really like it. The paratarp still goes as a "just in case" item when I don't plan to spend the night but want the option to, if I'm planning to camp I take the Megatarp. I used the Megatarp on a Canadian fishing trip a couple years back where we canoed and portaged to reach a lake in the middle of nowhere. Everyone with a tent and a Hennesey tarp strung over the tent managed to get water inside their shelter during one storm, the Megatarp kept me dry. I'm still not sure how they all got wet, their tent flys must not have been very waterproof anymore. Anyway I really like the room and size of the Megatarp for the weight.
We did have a 10x13 flat tarp we rigged up with a ridgeline and some guylines to trees as a place to get out of the rain and cook or hang out when it was storming to hard to fish. It was darn nice to have a place to do so, but I wouldn't want to have slept under it with a down bag.
The sheep tarp I think would be pretty narrow for what the OP wants to do. I'd want at least a 7ft wide one I think.