I've had some great ones lately.

Two 30 min bookings who paid for an hour as they were busy but know I don't accept 30 mins (one was only 20 mins and has already booked again)

One who I clicked with so well intellectually and who brought me a lovely gift (a book about electricity in the human body)

One who I experimented with (rope and nipple torture) - felt totally safe in his hands and had so much fun.