I've done an experience day and it was a bit lame, they do limit you and the courses are usually a bit oval. However this week I tried the carlimits one and they really let you just do it at your own level alone.
Not having a car worthy to do this in my own, I started off in an Elise with him sitting next to me, then he gets out to show someone else and leaves you to do it
solo. Till I found out my rear left tire had a nail in it. Then changed to the Boxster.
Only down side I'd say is when you do the circuit at the end, it was very short, about 3 laps around a minute each.