I did the 718 experience at Silverstone in May 17. drove 2 Cayman S (pdk and manual) and a Boxster S pdk over 2 hours with the same instructor - great fun and very informative
it was free at the time as a close friend was ordering a base Cayman at the time and his OPC offered him 2 places to "seal the deal"
not so free 18 months later as I picked up a Cayman GTS 3 weeks ago
I can see the attraction of driving a 911 but you may well got more out of 90 minutes in a Cayman - you wont believe what these cars will do until you track it - I recall the instructor telling me to commit into what looked an impossible right hander at 110 mph in the cayman S and me cowarding out leading to a messy effort (car still refused to let me get in real trouble) - next pass oh yes it will do that bend at that entry speed wont it.....
I have some track experience -- mainly on motorcycles, so I understood how a different platform could potentially behave on a track. Right off the bat I was lapping PEC Atlanta -- a very short and technical track -- fairly quick, and my instructor picked up on it right away. There is one compound parabolic curve at the back of the track that I had all sorts of problems with initially, though.
We took a break and played on the skid plate and slalom, during which we talked about that curve after my instructor noticed that I never looked at the cones while doing the slalom -- I focused on the end of the course. (A habit I developed from motorcycling). He said something that was like flipping a switch:
Basically, that on a bike it's natural and correct to look where you're going. But in a car, sometimes it's better to treat it like a golf putt by aiming at a point a foot or two in front of the ball instead of the hole itself, then doing that several times in rapid succession. It helps you push the car closer to its limits and hold a compound line.
By the end of the session I'd increased my trap speed in that section by nearly 20 MPH.
I'm tellin' ya, OP: do the Experience that matches the car you're getting. It is WAY valuable.