I would recommend 28x11x12" ITP Blackwater Evos for the rear and 28x10x12 for the front. It's a good all around tire, just stay off the pavement with them. If you want more aggressive for mud, there are a lot of options out there.
I say 12" wheels on 28's and down and 14" on 28's and up.
Some guys really like the 30" Evos. They measure about 28.5" tall. They're only offered in 10" wide but that fine. You can get them in 12" or 14" wheel size. My friend has them mounted on 12" wheels and they really provide a smooth ride and wrap around rocks.