My ideal realistic team looks something like
starters: Rondo, Pietrus, Pierce, Ryan Anderson, Garnett
bench: Bradley, JuJuan Johnson, Stiemsma, Pavlovic, Omer Asik (acquired in a sign-and-trade for Ray Allen with Jimmy Butler or a future first rounder tossed in), a couple of rookies with a defense-first mentality that earns them minutes (Ainge should avoid drafting anyone who projects to be a possible offense-oriented player with little defensive value), depending on how things shake out contract wise maybe Jeff Green and/or Brandon Bass, a D-League guard or wing who has the potential to be the next Wesley Matthews or Jeremy Lin. The Celtics may also have Rip Hamilton on the bench if there is a Ray Allen sign-and-trade to Chicago. If trading Allen to the Bulls isn't an option, then let him walk and look for the best lengthy center you find.
So, a team might look like
PG: Rondo, Bradley
SG: Pietrus, Hamilton, Pavlovic (for depth if there's not a good gamble out there)
SF: Pierce, Green
PF: Anderson, Bass (if he doesn't opt out), JuJuan Johnson
C: Garnett, Asik, Stiemsma
I don't have any strong opinions about who the first round picks should be used on, just that defense should be a priority, but I hope the Celtics can get Yancy Gates of the University of Cincinnati in the second round. He will probably be undervalued due to the UC-Xavier brawl and it would be nice to have a bench power forward who doesn't need to put on weight to become effective. Otherwise, just go for the best player available who you think can play defense well enough that Doc Rivers will use him.