Booked on Expedia...

I booked several places from Expedia a few years ago (Germany,Amsterdam, Paris & London). I didn't contact the specific hotels and never had any problems with the reservations. I did take my confirmations with me.

I use Orbitz and generally pack around all the printed stuff I could get from them and have never had a problem either in the US or international. I walk up to the desk, whip out the appropriate piece of paper and go from there. When I leave for a trip my file is usually pretty thick. By the time I get home, I've either thrown it away or it is basically an empty folder.
I think I worry and overthink way too much.

I would login to your account to make sure and the reason i said that is because I booked two nights in Venice and even though I received a confirmation via email the reservation did not go through because i did not activate my card credit! The only reason I contacted the hotel was for directions because Venice is very confusing. They told me I did not have a room so I called Expedia and the CSR directed me to my account and showed me where I could find the info on the account.

It looks like I'll just take my confirmation email print it out and take it with me and show it to them. I was charged for it on my debit card and I have a confirmation number for the hotel that was included in my email from Expedia.

Just for peace of mind, I usually email hotels directly when I've booked through another site. Sometimes I have a special request (non-smoking, beds etc) or ask for directions, or notify of arrival time. Can't hurt, right?

Chani, has the right idea. You can always just ask for a confirm directly via email: Its free.

I, however, never book the hotel and the airline in one package. There are no real savings, at least I've never found this to be the case, and it messes up your options to be where you decide to be.