Hey Greg, I've fit a 12 lb briskie in the #2, but it's all about the length. I've seen 12 pounders that were 15-16" long, and some that are about 18"! That's why I like to hand-pick my briskets! I like the "short and stout" models!
Lots of great brisket methods here, from simple salt/pepper/smoke it, to complex - your choice! I've gone to brining briskets, and really like the results. I use my pork butt brine, then coat with Jim Baldridge's Secret Seasoning (of course, other rubs will work), and smoke with mesquite. Here's my first brined:
Brined Whole BrisketWalt has a great method, too, but requires a lot more time:
Walt's Brined and Injected BrisketAs you can see, lots of ways to go! Try a few methods, and see what works best for you.