im on 1stgen and i get 5 hours non stop web surfing fun/musics ect..
what you need to do is turn wifi off when not use turn auto brightness like 35% push 1 hour or manual turn keyboard clicks off ect..you get the idea lots out there on settings..
also when you got that set up try charging you iphone usb on your computer it charges the phone bit slower to full charge but you get better long run time than the ac charger..
if you need to travel then get one of this
mophie - iPhone Battery, iPod Cases, iPhone accessories and more! - Juice Pack - iPhone 1st Gen