Never did the "Captain's table" but on each of our two Seabourn cruises, the most recent being Alaska last fall, we were at various "crew hosted tables" such as the First Officer's table, the Cruise Director's table, a couple "entertainers'" tables, the "medical staff" table and so on. Other than Seaborn, however, we have seen very little evidence of the old custom. On the other hand, we always dine at main (early) sitting and maybe miss it.
Once, on the Celebrity, however, the Captain joined a couple of our youngest grandchildren and their fellow junior cruisers for hot dogs at their "pajama party" which I thought was really neat!