We, and the couple we travel with, purchased the entire package (air, hotel, transfers, etc.) directly through Princess. Although we could have done it at little more cheaply purchasing the elements individually, only having to deal with one entity if anything goes wrong, which it often does, is an advantage.
Fortunately, Princess had arranged our air from Ottawa through Dulles/Washington rather than the "normal" hubs of Detroit or Chicago. This enabled us to just miss the massive winter storm of 01 Feb that shut down most of the US mid-West and eastern seaboard.
On arrival in LAX, we were met at the baggage carousel by a Princess rep who waited with us for our luggage--in vain! She helped us find a United rep who located all five pieces of luggage for the four of us that, apparently, completely contrary to USTSA policy, had been shipped in on an earlier flight.
Note my above comments in regards to the erroneous emergency information on the back of the door to E701.