Expedia are one of my favourite internet companies
Expedia did an absolutely fantastic job on both my recent trips booked with them.
Not only did they pay cashback on the trip, when we had a problem with our hotel they negotiated with the management so we could move hotels (we paid for one night of a 7 day prepay booking). They refunded me the remainder of the money, and didn't even insist that I book the replacement hotel through them.
That is the sort of company you want to deal with, so I did book a new hotel in the same place through them and got cashback paid on that one also. That covered the one night cost at the previous hotel.
You have to wait until you take your trip for the cashback to be paid, but that is entirely reasonable for me.
Good job Expedia.