Also, fyi there is no A350-1000 to anywhere in the USA except SFO for now. IAD had it briefly at launch but it was quickly downsized. For US East Coast: A359 serves EWR amd IAD. 77A/H flies to BOS and JFK. There is presently no easy coast 77G/77K service, nor A350-1000 service.
A few resources: check our FAQ. Also check the wiki in there with a link to CXs fleet information and which routes get what and when. Here
Cathay Pacific and Cathay Dragon Fleet Route and Configuration Guide
Although it is a pain in the butt to search on FT, if you can afford 15 minutes you'll get more info than you ever wantB and definitely more than will come here inia single thr ad. n Business class seats and longhaul flights are very popular threads.
Tonseof threads on the different biz seats and biz service, probably most posted topic. Although searching sucks on FT, use the advanced search when possible.
Also fwiw IAD is just a typical late night CX departure ex-North America. Discussions on most the other flights will be relevant too if you're looking for service timing / style related questions. The destinations themselves don't make much difference. The plane type and time of day of departure do.