I'm actually surprised that there isn't more support for letting him walk. I love him too, but Paul's leg's are done.
The Celtics came within one good quarter of winning the NBA Finals. I'd say Pierce's legs are doing fine.
As far as how much we pay him goes, I don't think the amount really matters, just the years. Based on the figures I've seen, the only way we can get far enough under the cap to sign a worthwhile player this season is if we renounce Ray's Bird Rights, Sheed's contract comes off the books and Pierce accepts about $6mill per! (That would get us about $10mill to throw at someone).
So if it takes up to about $20 mill per to resign Pierce, but keep his contract to two years, I'd do it. More likely, he'll want at least 3 years, in which case, hopefully we don't need to offer him more than $15 mill per and we can front load it.
I'd like to see Ray back, but the way he disappeared in the Finals after game 2, I think Ainge has to consider what options he has there. The Warriors have a lot of useful (and redundant) pieces and certainly seem to be open to ideas that reduce long-term salaries. IF we can get frontcourt help and still end up with a decent shooter in the backcourt, then Ray is the guy to give up in a sign and trade.
Dream scenario: sign Ray to a one year, $12 mill deal, trade him to the Warriors for Biedrins and Azubuike. Add some cash for the Warriors so they can buy Ray out during the season and we can get him back. The Warriors get rid of Biedrins contract and the Celtics get frontcourt help for KG and a nice wing with size and shooting in Azubuike, as well as hopefully getting Ray back during the season. (Yeah I know, Ray would be tough to convince).