Ideally, we would rank the top 8 teams and have them play it out. Inevitably, certain conferences (and Notre Dame) might be left out in certain years under that system, and unfortunately, that is unpalatable to conference commissioners and school presidents. We all want a playoff, but we all have to be realistic and must understand that some concessions have to be made in order to have a playoff system in this construct that we currently have. A playoff will never happen without the support of the six major conferences, the support of the BCS bowls, and the support of the Notre Dame administration (as much as we hate to admit that). There is simply too much money involved and each of those entities must have some incentive and involvement to support a playoff system. Additionally, there must be some value given to the regular season and a conference championship to satisfy traditionalists. There is something to be said about preserving the value of the regular season and maintaining the importance and tradition of conference play and rivalry games.
I would have an 8 team playoff, with 6 of the teams comprising the champions of each of the 6 major conferences (big 10, big 12, sec, pac10, big east, acc). The other 2 teams would be the highest ranked teams in the BCS standings who did not win their conference. If Notre Dame or a mid-major was one of these teams, then they qualify. If Notre Dame or a mid-major finishes in the top 6, they automatically earn one at-large bid over any other team (a playoff system has to have the support of ND, as much as we might lament one school having such influence). For this system to work, the regular season would likely have to be shortened by 1-2 out of conference games to satisfy the NCAA and preserve academic integrity in the sport.
Teams would be seeded based on the final BCS rankings. The first round of games would be played at the higher seeded home team's stadium. This rewards a team for an excellent performance during the regular season. The 4 losers of the first round would then be eligible for selection to non-BCS bowl games. The winners would advance to semifinals (two games) to be played at two of the BCS bowl sites. The semifinal winners advance to a championship game (3rd BCS site). The losers would advance to a consolation game (4th BCS site). The semifinals, championship, and consolation games would rotate between BCS sites on an annual basis.
In 2007, with this system, the teams involved would have been the conference champions (OSU, LSU, VaTech, Oklahoma, USC, West Va) and the next highest ranked teams, in the top 8 (Georgia and Missouri). Teams would be seeded according to final BCS ranking. The first round of this playoff and bracket would have looked like this for the past few seasons:
West Virginia @ Ohio State
Georgia @ Oklahoma
Missouri @ VaTech
USC @ LSU
2006 season (michigan/florida controversy):
Wake Forest @ Ohio State
USC @ LSU
Louisville @ Michigan
Oklahoma @ Florida
2005 season (USC/Texas game)
Florida State @ USC
Notre Dame @ Ohio State
Georgia @ Penn State
West Virginia @ Texas
2004 season (Auburn gets snubbed despite going 12-0)
Pittsburgh @ USC
Utah @ Texas
VaTech @ Auburn
Michigan @ Oklahoma
2003 season (USC was AP, Coaches#1 but left out by BCS; BCS was determined largely by computers at this time)
Kansas State @ Oklahoma
Ohio State @ Michigan
Florida State @ USC
Miami @ LSU
Of course, Kansas gets left out of the party in 2007, Boise State in 2006, Oregon in 2005, Cal in 2004, and Texas in 2003, but again, some team will always feel jilted in any system where only a finite number of teams are invited to play. Only two teams from the same conference realistically can be in the tournament in any given year in this system, adding even more importance to the regular season. This is why you MUST win your conference to guarantee your place. Additionally, some people might say that this system is unfair to mid-majors. Teams from the WAC, MWC, SunBelt, and MAC can get to the dance if they schedule and defeat hard, OOC foes from major conferences and dominate their conference slate (i.e. Utah in 2004). The one anomaly above is the 2003 season, where Oklahoma got routed in the Big 12 championship game 35-7 by Kansas State and still was ranked #1 in the final BCS standings. In this playoff system with the 2003 BCS system used for seeding, Kansas State would have to travel to Oklahoma again in the first round after soundly smacking them in the Big 12 Championship. Of course, the BCS at that time was heavily based on esoteric computer rankings and not as much as on the human polls as it is at the present time. Surely, with today's BCS emphasis on human polls, those standings would have changed considerably and Oklahoma certainly would not have been ranked #1 after such a disastrous conclusion to the regular season.
Winning your conference gets you in but it might not necessarily earn you a home game or a favorable matchup in the first round. Seeding is based on BCS rankings, which essentially is based on the polls, so a conference champion would not necessarily be assured a home game in the first round. In West Virginia's case, their season-ending loss to Pittsburgh would send them to the Horseshoe in December for a first round matchup with the Buckeyes in 2007, rather than hosting a first round game in Morgantown. USC, which lost two games (one to Stanford), would have to travel to Death Valley to take on LSU. This might seem like a terribly tough matchup in the first round, but both of these teams had two losses and the BCS ranked them where they ranked them. No system is perfect, but anything is better than what we have right now.
This analysis holds even more true in 2006. Wake Forest won a weak ACC conference and would have to travel to Columbus in the first round. USC, the Pac-10 champion who lost to UCLA in the 2006 season finale, would have to travel to LSU, who didn't even win the SEC. Similarly, Louisville and Oklahoma would have tough opening round matchups with Michigan and Florida.
Bottom line: A team that has an impressive season is rewarded with a home game in their home stadium with the most favorable matchup possible. In college football, home field advantage is paramount. Imagine if an SEC team had to play in Happy Valley or the Horseshoe in December, or the converse of a Big Ten squad having to go the Swamp or Death Valley.
Hopefully this would encourage teams to schedule competitive, out of conference games. If a team won such a game, they could elevate their ranking and seeding in the BCS rankings. If they lose such a game, they could still get into the playoff by winning their conference. Unlike the current system, there would be little to lose and much to gain by scheduling tough OOC foes. Tradition is preserved and the importance of the regular season, if anything, is increased.
BCS involvement, unfortunately, is critical. Bowl administrators and TV executives are probably fearful that they would lose money in this system, but in reality they should clamor for this playoff system. Right now, too many teams are included the BCS and the quality of games is diluted. ABC had excellent foresight when they decided not to renew their contract with the BCS. There have been only two competitive games in the past two years (boise state/OU and kansas/VT) in this current 5-game format. Ratings have been abysmal for the other games, probably because many of these matchups lack national appeal and because there is rampant resentment towards the current BCS system. In this proposed playoff system, every BCS game matters (with the exception of the consolation game, although that might attract more viewers than current BCS pairings). In this system, three BCS playoff games have national title implications, not just one, and the consolation game would match up two of the top four teams in the country. The championship, consolation game, and semifinals would rotate through all four BCS sites. You would have to believe these games that determine college football's national title would earn higher ratings than Kansas/VT or Wake Forest/Louisville.