Where is the best place to put a hottie to warm the whole body?

If by "hottie" you mean a guy who turns you on, I suggest the "Missionary position" as generating the most heat. If you mean something like a hand-warmer, I'd suggest getting an electric blanket, heated throw, or, to save the most energy, a "rescue blanket" of aluminized mylar. With the last, you will be peeling it back in a few minutes to keep from overheating.