Do you have tow hooks now? If not, you can usually find them online, or just order a set. If you put one of those cheap pushbar/grill guards on..they use the OEM mounting for the towhooks, and you'll have to remove your fully functional towhooks for a cheap cosmetic item that offers no real protection or functionality (you can't use the grill guard as a tow point if you need a tow...it will rip right off.)
As far as the whole MT vs AT debate...get what works for you. A lot of MT's aren't as capable on wet pavement or ice as AT's are...so if you think you'll be driving more in those conditions than off-road, I'd stick with a nice aggressive AT tire.
Also, depending what you intend to use your Jeep for, you may or may not feel the need to regear after going with bigger tires. I have 265/75R16's on my Jeep...and according to a few, I was going to hate the "loss of power" and would shoot myself if I didn't regear to 4.10's. Suffice it to say, I couldn't care less. I notice the difference, but it's not so dramatic that I feel it needs corrected. However, I don't trail ride much. So for those guys who put the Liberty through some inclines and crawling, I could easily see their argument.
So again, keep in mind your intended purpose when making mods.