A Cunard cruise is on our short list of things to do in the very near future. In fact, since we love cruising for the sake of cruising and are not really interested in visiting a lots of ports of call...many of which we've already visited....a Cunard trans-Atlantic cruise is right up our alley.
As to table size, we've done everything from a table for two all the way to a table for twelve.
Bottom-line, I think we prefer larger tables. We're both outgoing and can find interesting things to both talk about and learn from a diverse group of people. We're used to dining as a pair and have no problem with that but like the camaraderie of a large group.
But as this thread indicates, each to his/her own.