If you have an arena focus, you'd want engineering on everyone.

If its more for general play, you have a lot of options.
You could go Inscription, which also means you don't need the faction for shoulder enchants (Hodir in WotLK).
You could have professions for transmutes.
The jewelcrafting daily is lucrative too.
It will be a good idea to have Enchanting on someone on the team, if you PvE instances; that way nothing is wasted.

The gathering skills are an amazing way to make gold, when you don't have much.

The production skills (buy mats) make you a lot more, particularly as you attain rare recipes, or even reputation recipes.