For a different take on Bass Lake history, read Hells Angels: The Strange and Terrible Saga of Outlaw Motorcycle Gangs by Hunter S. Thompson. A good read on the Wild Western.

ankopsu Article on Bass Lake

My advice would be to do as many excursions as you can. They are a great way to get to know your group, and they are always good fun.

Mike Contiki Article on Optional Activities - Europe

If you are doing a time out tour (staying in hotels), a travel iron/hairdryer will come in handy as many european hotels do not provide these facilities.

Vicki - Contiki Staff, Europe Article on Suggested packing list - Europe - Summer