We used Prague Airport Transfer with the option 'minivan, 8 people - for 990 czk' and was very happy with the service! It seemed to have been a small misunderstanding where we were supposed to be picked up, but the driver called us and solved the 'problem' really quick. We got help with our luggage from the friendly chauffeur, and at the car we were provided with both water, a tour guide book and a map. There was a quick ride (25-30 minutes) to our hotel in central Prague, and when we a few days later booked a ride back we got the same driver again.