Do You Open Presents on Christmas Eve or Christmas Day? [POLL]

Christmas is my favorite holiday.  Sure, I like getting gifts; but I like giving gifts just as much, if not more.  Growing up, we were only allowed to open one present on Christmas Eve; and the rest had to be saved for Christmas Day.  I actually kind of liked the excitement that would build over the course of that one night, over both the gifts I was giving and receiving.  My fiance's family puts more emphasis on Christmas Eve, though; so now I kind of get to do both (which is fine with me)!  It raises an interesting question, though...

For the longest time, I wasn't even aware that some people open all their gifts (and do most of their celebrating altogether) on Christmas Eve.  So I'm curious: which do you prefer?