Great pictures Patty.
We thoroughly enjoyed the Viking Top of the World Tour and Cruise. We returned Sept 5, 2004.
Lhasa is well worth the extra days. You should take it very easy the first day In Tibet to adjust to the thinner atmosphere. If you don't over do on the first day you will be ready for all the exciting things that follow. The Viking staff will tell you this over and over and encourage drinking plenty of bottled water while you are there. Follow their good advice.
From the Great Wall through the Potala Palace to some of the longer climbs from the docks on the river up to the buses waiting in the cities...it can be a strenuous tour. Wear good walking shoes. China is an amazing awesome country experiencing rapid building and economic growth. We would recommend the tour highly. The staff on the river cruise were outstandingly friendly and helpful. Our Viking escort, David, was great. Say hello to Pim in Lhasa from Don and Jo Ann if he is your guide. Do take the Tai Chi lessons offered each morning on your cruise. Jo Ann