I have given up on two parters at the moment as my thirteen month old just wriggles all the time. She did 5 flips onto her tummy when i was trying to put a two parter on her today. Pockets for the time being!!! If i don't start using pockets i might end up mad!!!
I have to vote for the Rabbitt Mat too, although the last couple of months we haven't needed it, seems she has grown out of being wriggly but I am keeping the mat for the next one as I am sure it will come in handy again