If you are in bad cell coverage (which eats more juice) or are a heavy user, pray god invest a few bucks into a Gumpack external battery. That thing is half the size if a pack of cigs and stores enough juice for 2-3 full recharges on the go. Its one little more gadget to toss into your daypack and remember to keep charged but its well worth the bother. Certainly easier than speculating about a bigger battery while batt life is fine for most users.
And I am not bashing, if you have a 1.5h commute to work and spend it playing GTA3 i can see where the juice goes. So a gumpack battery would be your best approach, with the current 28nm Krait architecture there is not a lot to gain batterywise really. Plus, the AMOLED sucks less juice on dark images, something to keep in mind when picking a background image I think.
(There are also cheaper competitors offering similar devices if you shop around...)