I somewhat of a fan of the BCS, and although this year is an aberration, I agree something needs to be done. Even a four team playoff would leave out an undefeated team. An 8-team playoff is overkill, diluting the reg season.
Maybe something like HOF voting. Voters give a list of the teams they want in the playoffs, and the teams in must get at least 75% of the vote. Take a min of 4 (some might not get to 75%), up to a max of 8. This year you'd presumably have 5 teams, with Cinny playing BSU as 4 vs 5, winner playing Alabama and Texas playing TCU. Most years a 4 team playoff, no more than three rounds, no "filler" teams that shouldn't be there.
Probably a dumb idea, but I like it.