Two smoker-loads: Brisket and Butts

I would cook the button then vacuum bag and freeze them whole, really heat in boiling water then pull

First do the math. 100 people will eat about 1/4 to 1/3lb of meat per person assuming a good supply of sides. Be conservative and say 1/3 lb. Therefore you need about 35lbs of finished product.

Let's say you doing 15lbs of brisket and 20lbs of pork.

Butts will yield 50% of precooked weight so 4-10lb butts gets you 20lbs cooked and pulled.
Briskets yield a little better around 60% of precooked so 2-13lb briskets gets you there.

Both meats will benefit from a long rest in a cooler. I've held butts 4-6 hours in a cooler and they are still too hot to handle when you pull them. I also think butts are more forgiving so I would do them first.

Then do the briskets hot and fast and still allow a few hours for them to rest in a cooler before you serve.

Sounds like the Perfect Excuse to add another cooker/smoker......
WSM or Pit Barrel or UDS or Cabinet Smoker - or even a 26" Kettle...... :heh:
OR Even Better: an Old Country Smokehouse and you can get it all Done in 1 Smoker.....

Sounds like you have a good plan formulated..

Years back when I owned a share of a catering company, we took a look at how many men, how many women, and how many kids as they all eat differently.

Men will generally eat 2 sandwiches each of about 1/3 pound per sandwich.
Women will generally eat 1 sandwich of about 1/4 pound per sandwich.
Kids waste food. That's an undeniable fact. BBQ is expensive. Get a setup supervised by an adult and have the kids, anyone under 12, cook their own hotdoga. They absolutely love doing it. Again, BBQ is expensive and hotdogs are cheap.

To augment the calculus, serve big bags of popcorn sprinkled with a bit of the rub that is on the meats. Serve a vinegar based cole slaw. It's inexpensive and comes together quite quickly. For the other side, serve baked beans. Forget potato salad. It's labor intensive and thus not something you want to spend a lot of time on. Further, you don't want anything that is mayo based this time,of year and give everyone a case of food poisoning. Deserts are just cobblers, dump cakes, or crumb topping variations of the cherry, apple, berry, or peach cobblers.

I hope this help you and gives you some ideas as to how to figure how much to cook. The above calculus never failed us.