Textured ceilings are rather simple, but you're kind of limited on what you can do afterwards. 'Knock-Down' finish (which is what we usually do on whatever we build) works good on walls and ceilings and will hide a lot of things. It's messy too, just like anything that will get applied to sheetrock.
Knock-down is just thinned drywall mud sprayed on with a texture gun, then lightly troweled after it dries a little while.