I want to make myself a sleeveless wrap top, out of dk weight cotton. I'm designing it to be knit in one piece on a circular needle. I don't have a needle in the proper size, so I'm trying to decide what size to buy. I'll probably get a size 5, but I'm unsure as to what length I'll need. The finished size of the project will have to be 60" at the hips, since it will wrap around. Would a 36" needle be long enough? Or should I try to find a longer one? Thanks in advance!

A 36" circular ought to be just fine! You won't need a longer one...

A 36" one will do just fine. The cord is about 8" shorter than the full needle length and they hold something like 3x that in stitches...