Put in a drop ceiling for sure I just finished mine looks great and is very functional for access.

www.armstrong.com and www.usg.com are the two major manufacturers

Take a look at Armstrong's Ceiling Max (at HD, among others) if you need every inch in height. Sort of like a drop ceiling, but you attach it to the bottom of the joists to save inches. Home Depot has a display, sort of. BTW, it's easier to install if you finish the walls first.

I would definitely use drop ceiling because if you ever need to access anything it is much easier to access then cutting a hole in drywall. There are all types of drop ceilings--wood, tin, fake wood that looks real, gypsum, etc. The company we are ordering from is www.iscsupply.com They seem to have good prices and a good selection and the sales rep I talked to was very helpful. I was pretty excited to see that there was more than just plain white tiles!

Here is a link that might be useful: ISC Supply