I don't think GSW or Denver make much sense at all. They've both got very able long-term solutions at the 3, and any cap flexibility they can grant Pierce isn't going to get them far enough down to do anything special.
Golden State makes a lot of sense. They are a likely tax-paying team who have a big contract for a useless player (Biedrins) and more money tied up in a player they don't need in Richard Jefferson. The problem is that Biedrins has a ETO and Jefferson has a player option, which makes the timing of a trade a bit problematic.
A true blow it up trade would be Pierce and KG (if he agrees to waive his no-trade clause so he can head west with Pierce) for Biedrins, Jefferson, filler, and first-round picks, at least one of which is far enough in the future that it is likely to be available when PP/KG are gone from GS and the Warriors have a chance of sucking.
The reason why Golden State doesn't make sense is because even if you're considering Pierce a straight salary dump (as in, they're waiving him after unloading Jefferson and potentially Biedrins), who else is Golden State sending back?
They've got to resign Jarret Jack and Carl Landry. They'd love to unload Richard Jefferson and Andris Biedrins, but the Celtics would need someone back. The best Golden State seems to be offering are picks starting in 2015 at the earliest, and potentially Brandon Rush.
After the most successful playoff run in almost 40 years, who are they going to gamble on replacing?
And last but not least, why would GSW possibly pay Pierce? They've got a player with the potential to be truly special in Harrison Barnes, but they're going to eat up his minutes in the least with Pierce at the 3? Just doesn't make sense.