The following are my choices for the next Titans Head Coach, in order and why:

1. Marty Mornhinweg - Offensive Cordinator Philadelphia Eagles - I like that this guy has head coaching experience.  He coached the Lions in 2002 and 2003.  He was unsuccessful, but it has been almost 10 years since that experience.  In that time, Mornhinweg has been a very successful offensive cordinator.  This guy is also very successful developing QBs, which could really help the Titans this offseason.  He has had success with 3 different QBs over the last 3 years.  His hiring could also help bring about a possible trade for current Eagles backup QB Kevin Kolb.
2. Gregg Williams - Defensive Cordinator New Orleans Saints - Like Mornhinweg, I like that Williams has head coaching experience.  He was the Bills head coach for 2003 and was only given one season.  He was 6-10.  Since leaving the Bills, Williams has been a very successful defensive cordiantor with a number of teams, including winning a Super Bowl with the Saints last year.  Williams is well known to the Titans.  He was the Defensive Cordinator for them in 1990 when the Titans went to the Super Bowl.  One advantage Williams has is that he is familiar with the holdover assistant coaches that the Titans have already signed.  He can keep the ones that are good and pluck the rest from staffs he's been on the past decade.
3. Brian Schottenheimer - Offensive Cordinator New York Jets - Schottemheimer has good bloodlines as his father, Marty Schottenheimer was a successful NFL head coach.  Schottemheimer has been a very successful offensive cordinator.  He has been with the Jets the past 5 seasons and has been a part of their playoff success the past 2 seasons.  He has also been instrumental in the developing of QB Mark Sanchez and also helped develop Phillip Rivers and Drew Brees.
4. Mike Mularkey - Offensive Cordinator Atlanta Falcons - Mularkey is a long time offensive cordiantor who has worked with the Steelers and Falcons, among other teams.  Like Williams, Mularkey has also been a head coach for the Buffalo Bills.  Mularkey ran the Bills for two years, so he would bring head coaching experience to the table.  Mularkey was also key to the development of current Falcons QB Matt Ryan. 
5. Perry Fewell - Defensive Cordinator New York Giants - Fewell was the defensive cordinator in Buffalo in 2009 when then head coach Dick Jauron was fired.  Fewell took over as the interim head coach and finished the season 3-4.  So Fewell has at least some head coaching experience.  Fewell had a very successful first season as the defensive cordinator of the Giants last year and is considered an assistant coach that is on the rise.