There are no published goals needed to make PP other than being in the top 3% of members in the program. They don't say what makes up the 3% either, so it could be any combination of nights, stays, dollars spent, number of days holding a reservation, or how many MR executives have the same first name. Since this is a moving target every year, the best you can do is pour all your stays into MR and hope you break the tape.
Personally, the one year I had it (the last year they did the dining discount) the dining discount was the only benefit I liked. From my reads today, there's little, if anything, worth while in the status, unless just the fact you got the brass ring means anything even if you have no where to toss it.