I fully support a 4 team playoff.
This would keep the regular season very important, losing a single game puts you in jeopardy of missing the playoff, and losing two eliminates you 99% of the time.
We already have a 2 team playoff so expanding it to 4 is a less dramatic step than to a larger number.
And as others have pointed out, you are playing for #1 so #5 really has no business complaining. They WILL of course complain, but to hell with them.
Expanding the playoff to including too many teams (8 or even some people say 16) is just far too many. It would make the regular season much less important. You would have many two loss and even three loss teams making it every year. Also the preseason polls (which are a load of crap and should be abolished) would decide which 2-3 loss teams actually made it, as there are MANY 2-3 loss teams at the end of the year.
Also -
Carl from Aqua Teen Hunger Force talks about the BCS