Should I be concerned about graphics switching for battery life?
Absolutely ! http://codekrieger.com/gfxCardStatus allows you to lock your graphics card to use only the Intel integrated graphics. It makes a big difference when you need to squeeze every last hour out your battery.

The other thing that helps if you have a ton of startup items for everyday use is to hold down shift when you log in, so there are not extraneous processed running in the background.

And also keep the screen brightness at the minimum acceptable level.

This way I can get 9 hours out of my 17 macbook.