assuming House stays put this would be my ideal (and fairly realistic) off season.
First, re-sign Davis at 4 years, 15 million or somewhere in that range. That rewards him for good play, but doesn't overpay.
Second, use LLE (or vet minimum) to sign Anthony Carter to a 1 year contract.
Third, sign Zaza Pachulia to a 3 year contract in the 10 million range preferably by doing a sign and trade with Atlanta in which we ship off T. Allen and 3 million cash for Zaza (atlanta thus nets 500k). If not use part of the MLE.
Fourth, use part (or rest) of the MLE to sign Grant Hill/Wally Szczerbiak/Desmond Mason, whichever we can get for a one or two year 2-3 mill per year offer.
Fifth, if able to do a sign and trade in 3 or 4, then use rest of MLE on Shelden Williams (assuming the team option is not exercised making him unrestricted). Give him a 2 year deal worth 5-6 million. If no MLE left then re-sign Powe or bring the Turkish kid drafted last year over to fill out the roster.
Thus, the Celtics entering next season would be
Rondo/Carter/House/Pruitt
R.Allen/House/Giddens
Pierce/(Hill, Wally, Mason)/B. Walker
Garnett/Davis/S. Williams/Scalabrine
Perkins/Pachulia
The C's have a lot of flexibility as they could easily go big or small depending on matchups and the lineup would provide more cover to the starters.