Do you use task manager to shut off active applications that you are not using? If you have WIFI off and GPS off the only two things I can think off is either you have a bad battery that discharges too quickly or you spend lots of time in a place with no signal or a very weak signal. The phone will use more power to stay linked to a very weak signal or constantly try to connect if there is no signal.
Same here, in my area I only show 1 or 2 bars. I've been told the strength indicator with eclair 2.1 isn't very accurate, go figure! Go into settings, location & security and be sure that VZW location services and standalone GPS services are not checked. These are not needed unless using the GPS. Actually when using GPS I only have checked the standalone GPS services and Google location services.
Instead of using the built in task manager, I use an app called NetQuin Android Booster which is very good for stopping tasks from running except for those that automatically restart themselves. NetQuin also has a good anti-virus called NQmobile Anti-virus.