Since I work at the BB, here is what the plans do and do not cover:
The most expensive plan is the 3 yr, ADH or accidental damage plus parts and labor
The only thing that this is not going to cover is if it is lost or stolen, burnt in house fire or if you drop it in water. It does cover if you spin water or coke, just can't take it swimming with you. For the MacBook that should be around $379.99, there is a 2yr option, it is only $50 dollars less.
The next step down from that is Best Buys parts and labor coverage.
This is going to cover: Dust, Heat, Humidity, Regular Wear and Tear, it also covers a one time Battery Replacement, if the LCD screen goes not (not damage) as well as the charger. This option should run you $100 less than the ADH plan, so if the 3 yr ADH is $379, the 3yr p&l labor would run $279.
If neither one of these float your boat, you can purchase a 1yr, ADH plan for $99
We sell alot of these with our Apple portables, because alot of people love Applecare, but they don't cover damage.
I will say that I have AppleCare on my laptop, and while I have used it more than I should, I am glad that I bought it, as it has already paid for itself, and the turn around time is super fast. I however did not buy my laptop from Best Buy, although I work there.