I would at least give Gary Patterson a phone call to see if he's interested. Otherwise, here's my top list of realistic candidates.
1. Les Miles -- The man knows what it takes to win in the SEC and can potentially tap into the recruiting in the talent-rich Louisiana area. Also, he has won multiple NC's and would be a very "Philip Fulmeresque" hire.
2. Tee Martin -- Really enjoyed watching his offense during the PAC 12 championship game and would bring an exciting brand of football back to Tennessee. Also, given the trend of alma mater coaches having success (Kirby Smart, James Franklin, etc.), he would undoubtedly understand what it takes to be great at Tennessee.
3. Mike Norvell -- Hiring him would essentially be hiring Justin Fuente 2.0. Justin Fuente essentially learned his entire offensive scheme from Mike Norvell at Arizona State that he used at Memphis and is now using at VT. Memphis has an excellent offense and puts up huge numbers despite having lost talent to the NFL. His defense is questionable however.