Adam,
Steve gave you a solid plan. I will add that I don't think that amount of brisket will feed 29 folks, if that's the only meat. You'll lose about 40% of weight by the time they're done, so you're probably only looking at around 10 lbs of cooked brisket. It may make it, if not everyone eats brisket, but since you're making burgers and chicken, you'll be fine.
I'd plan on getting them in early morning, tomorrow (like around midnight/1 am). Even though there are 2, they would cook like a single. I think you'll see 9-11 hours (I smoke mine at 225, with a water pan on the floor of the smoker, and about 6 oz of hickory, mesquite or oak). Then, double-wrap in foil and place in an empty cooler, with a towel in the bottom. Then place another towel on top, and let them rest for at least an hour. Longer is OK, if they're done early (3-5 hours, like that, is no problem).
I also wouldn't rotate them, just put the biggest one on bottom, fat-side down.
Let us know how else we can help!!