I didn't need more airspace work, as I did my towered airport endorsement on my Sport ticket. I think I had to do 3 solo landings at a towered airport to satisfy the PP req't. I'd also done lots of solo flying as a SP, so those hours were covered.
As a SP I flew plenty of cross countries that were long enough, but they didn't have two stops so I had to do one fresh solo XC. Also, SP requires fewer hours of XC with an instructor than PP, so I had to fly a short out & back with my CFI to check that box. Then I had to do night work, and some more time on instruments (I think a couple of hours). All told, I had about another 10 or 12 hours of instruction - roughly 2 hours instrument, 4 hours at night, 2 hours dual XC, then a few hours brushing up on landings and maneuvers and emergencies for a new check ride.
The instruction was pretty simple; mostly just flying with an instructor as a passenger to rack up enough hours. I did PP in the same LSA I used for SP and had been renting, so I was very familiar with the plane. The checkride was straightforward and only took about an hour.