This may be the most reliable sports talk radio topic to stir a debate but here are my $0.02. The challenge is to balance the traditions that make college football great and have a logical way to determine a national champion. The biggest affront to the old system is the creation of the large conferences. First the SEC, then Big 12, soon the ACC, and then maybe the Big 10 (if ND ever takes the plunge). As much as I hate the Conference Championships they would be necessary if you want to even try a playoff scenario. As for # of teams for the playoff: 4 is too few because you have 5 big time football conferences (Big 12, SEC, Big 10, Pac 10, ACC). [The remnants of the Big East are not on the same level.] You don't want a champion of one of the 5 not in the playoff and also it is too narrow a window for a BYU in '80 or TCU '03 to develop.
So, now the question is 8 or 16. IMHO, 16 is too many not because of the extra playoff game it would cause but rather if you leave 9-16 available for the lessor bowls then TV & sponsors could create enough interesting matchups where it would not totally devalue them. So, 8 seems to be a good number.
The champions of the major 5 are guaranteed in the playoff. So now you fill 6-8; allowing a TCU if warranted, independent ND or whomever. The process for picking the remaining spots (and seeding) should be done similar to the NCAA hoops process. If the committee wants to use the BCS as a metric fine, similar to the RPI in hoops. Using a committee to seed can be helpful in having 2 teams be matched in the playoffs that had played in the regular season. I also would recommend no more than 2 teams from 1 conference be eligible for the playoff.
From there, I would play the 1st round on the campus of the higher seed. As popular as college football is I don't think they could do 3 rounds of neutral site play. Also, it is a reward for the top 4 teams. Then you have 3 games left and can use the Sugar, Orange, Rose, etc and rotate them.
Other musts: play an 11 game schedule (no silly kickoff classics); committe must be made up of administrators from the C-USAs, Mountain Wests of the world in addition to SEC, Pac 10, etc; also the guaranteed 5 spots should be awarded to the top performing conferences on an annual basis using some type of formula (haven't nailed this part yet).
Final thought, this playoff would not diminish the regular season at all. Since the BCS was created there have been very few teams go undefeated through the regular season. It rarely happens....When UT or Tenn or OSU has lost this season it's not like the fans just said "oh well...no MNC for us this year." I have never understood that logic. People still care passionately about the team. Also, it was mentioned that there are 15 good games this weekend, what?? OSU-UM, LSU-Ole Miss, then what? That point was used to highlight the significance of the regular season. The BCS has so isolated the landscape that the # of important games dwindle significantly each week. Another myth is the losing early is somehow better than losing late. Remember Nebraska getting the woodshed at CU a couple of years ago, then playing UM in the MNC? Another beef is that only the highest ranked teams can recover from a loss. These rankings come out so early in the season when no one knows anything. IMHO OSU is rated higher than LSU now because they were ranked higher coming into the year.
Oh well, done for now