I have no problem with PR becoming a State (or independent), but I think it's current status is unacceptable. All these inconclusive referendums need to stop. The Federal Government should tell PR to crap or get off the pot: 1 refereundum, Yes or No, whether or not to apply for Statehood, with the understanding that No, means independence. No more damn "Keep status quo" option available. The details of PR/US relations can be worked out after such a vote, such are whether they want a CFA with us.
Our other territories are a little trickier. They are frankly too small for me to want them to become States. Our Senate is already unbalanced enough due to small States without adding even more. I think perhaps all other territories should be made independent with CFA (of course, the US needs to actually start holding up it's end of the bargain better with our Compact partners, but that is a whole other issue....)
As for D.C., no to Statehood, yes to devolvement back to Maryland. Federal buildings would still be on Federal land, but everything else should be returned to Maryland. The original point of D.C. is no longer relevant in the modern era. In the beginning the States were equally powerful, if not more powerful, than the Federal government, and it could reasonably be said that the State hosting the capital would have undue influence.