Hi Donna,
I saw no one was biting, so I thought I'd put my 2 cents in...the 20% is in case people don't tip. Tip for excellant service, if your driver is great, then add whatever you want on...similar to server gratuity on ship, tip for what service you receive...if they are average, well they get the 20%. On a round trip that is like 15$ each way...If he is awesome, give him what you think he deserves in addition.
Question : How are you going to get all the bags for 7 people in the trunk?? they only fit 3 big bags...and a few small...I need packing lessons from you guys! LOL! Hope you feel better...pixie dust to you!
PS- You usually get the same driver going back...if you really want to make sure, pick up the phone in PC, call the 800 # and confirm...