Take into consideration how long you plan to keep it. If you are like my grandparents and plan to keep it for 30+ years, then it's probably a good idea to get the best you can. If you plan on replacing it in the next 4-5 years, it may not be as worth it to you. You really have to decide the factors listed above and your intended current use and intended (realistic) future use.
I'm planning on getting a 1080p tv. My reasons are I plan to keep it for a while, I sit closer than normal to the set, I'm pickier than average about picture quality, I intend to buy a HD/BD player, I watch a lot of movies (very little tv) and I am mildly paranoid about so called "future-proofing." However, I haven't completely ruled out a 720p set, I'm about 85/15 for 1080p. Once you figure out your intended use, it should become a bit more clear.
Jack