Relo day (the day when the Celtics open up the seat map and let STM choose new seats) is one of my favorite days of the year.* I really like my seats and probably won't move, but it's always fun to see what's available. I'm in the loge seats, so I can only report on loge--no access to balcony or the sections at each end of the court.
The trend has changed: In the past 3-4 years, relo day has been a mob scene in the loge. If you blinked, you probably missed the seats that you wanted. There was usually a lot of stuff on the ends, but very little in the middle of the court, particularly "Center 6" sections (11, 12, 13, 21, 1, 2). This year is the inverse. Lots of Center 6 stuff.
The most interesting is a pair of seats almost directly behind the Celts bench in VIP 21, in the second row of folding chairs behind the floor seats. The big downside is that they are in the middle of a row of 20 seats. The Celtics really need to space it out a bit. But they can be yours for $400/ticket/game.
Other goodies:
Loge 20, row 8, two seats in from the aisle: You're looking over the Celtics bench toward the court. $175 per ticket.
Loge 1, row 17, two seats in from the aisle: Dead center court. $245 per ticket.
Loge 4, row 8, on the aisle: $125 per ticket.
Loge 2, row 2: In the middle of a row but right behind the visitor bench. You can be a Weasley and throw snowballs at the back of LeBron's head for $295 per ticket (and a TP for the first person to give me the reference).
For those of you looking to move up, this might be the year. There's lots of stuff in 4 and 15, so I'm guessing that there's also stuff in the sections at each end of the loge.
Mike
*My favorite day of the year is the third Monday after Easter, when all the leftover candy goes from 50% off to 75% off.