Great thread! My extended family is quite religious and in fact my dad is a minister; but we always had Santa, Tooth Fairy, Easter Bunny, etc.. It never bothered me that there were multiple meanings for a single holiday (religious and secular). At one point when I was quite young I really believed Santa was literally true and would be amazed and thrilled when some of the cookies we'd left out were gone. I didn't have any particular "moment" when I realized otherwise, it was more of a gradual thing--recognizing the handwriting on the presents (funny how common that is--parents probably don't think their kids would recognize their handwriting that well!), trying to reconcile the idea of "presents for all the good girls and boys" with all the toy drives and poverty in the world, seeing all the different variations of Santa in pop culture, etc.. I'm an only child so there wasn't anyone for me to "preserve the magic" for, but I also knew better than to go around blabbing to other kids about my opinions.
I still think it's a fun, magical way of playing pretend and I never considered it lying, sacrilegious, misdirecting gratitude, etc.. I'm certainly not saying others are wrong to think so, just that this wasn't my experience, and if I had kids I'm sure I would try to set up the same thing for them. I do know a few people who are "militant Santa" who have really elaborate ways of supporting the facade, including codewords, and they get really, really angry
at even accidental suggestions that it might not be literally true (around their kids). Personally I think that's taking things a bit far, and I could see how if someone was familiar with a tradition like this, they might find it less than charming.
Anyway... I think I got multiple gifts from Santa, and also gifts from my parents. I don't remember any particular formula for it. We always did stockings first, then ate breakfast, then went into the living room with the tree to open the presents. All of the presents were wrapped. With only three of us in the household sometimes givers did not bother to write who the package was for and there were occasional gift mix-ups.
We never had much success at getting the stockings to "hang" so they tend to be propped up against the wall or laid out on the floor. I always do both my parents' stockings on Christmas Eve (both will give me items for the other one, if they have any) and then I cover them with a blanket, leaving mine out to be filled by my mom. My mom made all of our Christmas stockings by hand as well as many for our extended family, which is really nice I think.
We always have to travel two hours to see my mom's family on Christmas Day, a tradition I grow more and more tired of as fewer and fewer people attend, and we travel the farthest, so we have to rush through our own Christmas morning celebrations in order to leave on time, especially if the weather's bad. Sometimes we only open a few tree presents and then do the rest when we get back home that evening.
Also my mom and I give each other ridiculous numbers of presents, so we usually start opening a few in the days leading up to the 25th. We are not at all strict about it. I usually bring all the presents I'm giving to my parents' house a few days before the 25th and wrap them there. I still label things as being from "Santa" sometimes, if I get bored writing my name; also my dad, who is very difficult to shop for, is fond of buying things himself, for himself, and then giving them to me to wrap, so he can later open them, and I always claim that those are from Santa. We like to exclaim over the wrapping and the bows and read the "To" and "From" aloud. Actually it's mostly me and my mom, and my dad gamely plays along for as long as he can, then he gets bored and goes to watch TV while we continue on.