Buy the longest spokes you can and buy a Hozan spoke threader.
Otherwise.....
I'm trying to remember what I've used the most. Probably 290-302 for road wheels and 258-266 for MTB wheels. We don't screw around with BMX stuff at all. If someone wants one built, we can order them. They usually bring them in themselves, though. Usually neon green monstrosities from some obscure mail-order place.