Phnom Penh Cambodia Highlight
The trolley tour of Boston, offered as an optional, is the best way to see the entire city. Take it at your own pace, but I would suggest stopping off at the USS Constitution and Fenway.
I've found from experience the best and most reliable brand of adaptors for Australian travellers is Korjo. Check out www.korjo.com
I went on two tours alone...I made life-long friends along the way! That's the nature of Contiki.