my phone isn't quite that old, but it's a dumb phone, too, and only needs to be charged about once a week - with regular use.
i would get smartphones, though --- IF CARRIERS DID NOT REQUIRE A DATA PLAN WITH IT --- wifi connectivity for data is enough for me, i do not need, nor want, cellular-based data and the outrageous cost (compared to voice-only plan that we have now) that go with it. you should not be forced into a data plan if a phone has other ways to get that data (e.g. wifi).
hell, we don't even need a 'nationwide' footprint, our lower-cost regional plan (basically our state plus part of neighboring ones) is more than sufficient -- especially when something like skype-out over wifi would be available to use instead of roaming charges for that odd time, once every few years when we might find ourselves outside of the regional area... but soon after verizon axed all the regional alltel plans in favor of their more expensive nationwide plans, uscc (the only other carrier that can provision local numbers here) did the same thing.
so for us to get smartphones, we'd have to add not only data plans at an extra cost, per device, but also move to a more expensive nationwide plan besides -- our bill would be about $90 (uscc) -110 (vzn) MORE than we're paying now (plus the cost of the hardware)...
keeping our dumb phones seems like the smart thing to do.