I'm doing the same with my pork butt for July 4th (thanks to all the great advice I received from you guys in this forum). I'll be smoking the butts Saturday and pulling them, and then just reheating them on Sunday in a steam tray at the restaurant.
As for brisket, I don't see why you couldn't cook and slice them on the Saturday and just reheat them on Sunday as well- with a bit of the mop sauce, of course. The meat is already well done and very smoky, so you could just reheat it in a steam tray or oven instead of the smoker.
For that matter, cold BBQ brisket sliced thinly (and I mean paper-thin, like pastrami or Montreal smoked meat) is pure heaven as well. I've got an Oster home slicer that does almost as good a job as the big deli units, and it's cheap to boot. It works really well on both hot and cold meats, though the cold meats tend to stay together a bit better.
The only thing it doesn't do too well is cut brisket on the diagonal- I've got a big chef's knife for that. It works wonders on cold brisket, though. Just remember to pair it with a good mustard or BBQ sauce, and don't skimp on the quality of the buns.