Gasol will be the most coveted FA next summer, I don't think that the Suns will have a shot at signing him.
Love is in a weird situation: yes, his team wins more but his role is so much reduced that I'm not sure that he is happy in Cleveland. He might worth a run to convince that he would be the man in Phoenix while having a supporting cast of defensive-minded role players (Tucker, Len) and a dynamic backcourt-duo who also can play to his strenghts (pick-and-pops, outlet passes igniting fastbreaks, etc).
I think that there is a decent chance that he might listen to an offer like this.
Hansbrough is basically a min. FA.
Seraphin is a backup bigman at this point of his career but he has potential.
Jimmy Butler will stay in Chicago. It is also highly unlikely that Jordan leaves the Clippers plus we have Len so I would focus on the PF spot to upgrade.
Millsap is a good fit.