My electric mattress pad has wide elastic straps, not pockets. We have a double pillow top mattress, and it works just fine on the thicker mattress.
Snuggies look terrible, BUT, if I am in my own home and it keeps me warm without me having to turn up the heat and spending more money, then what do I care what it looks like. It's not like I"m going to go out in it (but people do. Snuggie Pub Crawls are becoming very popular).
I don't have one, and at first I thought they were stupid, but as the weather gets colder, I'm rethinking that.