I think you can bring Manu back for the vet minimum.
Paul's the first convo though. If he wants to come, figure out the cap gymnastics you need to make that work and do it (bonus if you can get rid of Pau or Aldridge in the process, like a sign and trade).
Probably worth talking with Pau about opting out with a promise to resign for less per year over more years (i.e., give him a 3 year 20 million deal instead of his deal next year).
Dedmon's probably getting the MLE slot (if they want to keep him and he wants to stay), you have the Arenas rule to keep Simmons too.
Side note, lots of people think Simmons walks / gets paid. I really think he gives the Spurs a hometown discount and re-signs with them. They gave him his opportunity, he probably wouldn't be anywhere near the NBA at this point unless he bought a ticket to a game. They can take care of him and I think he drinks the koolaid like Danny did a few years back.
Aldridge's contract is crushing at this point, particularly if he's going to continue to pout about playing the five and continue to be a gutless wonder in the playoffs when someone hits him in the mouth. Dude either needs to find some silver and black religion this summer, or the Spurs should make moving him a priority this summer too. He's still a relative bargain given the new max is about 10 million higher than he's getting paid, and he can clearly fill it up still if you give him the keys to the offense. Problem is Kawhi's emergence and their inability to play together (well, be efficient in doing so).