I thought our offer was better at the time, and history has proved that right. Only Golden State could have offered a better deal, in my opinion (it could have involved some combination of Biedrins, Ellis, Brandan Wright, Al Harrington or Adonal Foyle for contract reasons, and taking back a ton of salary with their trade exception).
The Twolves got one of the best offensive big men in the game, a versatile player in Gomes, cap relief, and a couple of draft picks (although it's likely that the Twolves pick they got back would have ended up being a #2). Telfair has looked decent at times, as well. That's a pretty good haul.
In terms of what the Celtics would have done, I was pushing for a Gasol trade at the time (so long as it didn't involve Big Al) so I would have been on board with that. (I noticed wahz mentioned this same idea on the front page). I'm not sure that Big Al / Gasol / Pierce / Ray / Rondo wins a championship, but it would have given the team a good front line to build around.