MacBook Battery Life Less than I'm satisfied with

I am enjoying my new Apple MacBook--a change of technology a choice deliberately made following the crash of my Sony Vaio laptop hard disk crash. However, it is disappointing how short-lived the battery is.

As I write this the machine is just off being powered with a full charge, and it reports 2 hrs 36 minutes of power left. I could get 3-5 hours on the regular Sony battery, and up to about 6-7 using the over-sized one I bought.

I'm pleased this is the "old" MacBook that has replaceable batteries. I've bought 2 extra.