While it's true that routine passenger service is a thing of the past, I think current day cruise liners can be used as a rough guide for the amenities aboard Traveller's larger liners. It's all about keeping the passengers occupied during the trip.
Once steamers took over the routes, Atlantic crossings took 3 to 6 days depending on the ports involved and the weather between them. The best liners weren't only just the faster ones, amenities counted too because, as Johnson once quipped, being aboard a ship is like being in jail with the added chance of drowning.
If keeping passengers occupied during a 3 day trip was important, why wouldn't it also be important during a trip which consists of 7 days in jump plus however long is spent in normal space between the ports and jump limits?
I once took a freighter from Charleston, SC to Valparaiso, Chile in the 1990s. A relative of mine was an officer aboard and offered me a travel to travel as a P.A.C; "person in addition to crew". I'd read that Alex Haley, the author of Roots often traveled in freighters as a way of getting work done without distractions so jumped at the chance hoping to get some serious studying done. I originally planned on making it a round trip. However, before the first week was over I was so bored that I flew back to the US from Valparaiso instead.
The food was excellent and each meal's menu extensive, the US Merchant Marine eat like kings. The officers and crew were pleasant, but they all had jobs to do and none of those jobs included acting as a cruise director for me. I found I could only study the materials I'd brought aboard so many hours a day before the law of diminishing returns set in. That left a lot of hours to fill and not much to fill them with. The tedium was broken by a few ports of call on the way to Chile, but I can imagine what 168 hours with no breaks would have been like. o:
Passenger ships in Traveller are going to have as many amenities as practical if only to keep the passengers from killing themselves and each other out of sheer boredom.
Yeah, but I gotta figure the free trader at least has a better selection of DVDs and video games than a seagoing freighter, since they routinely carry passengers. Not sure what else might be available. Only way I can figure to cover a free trader cruise with one steward is to give him an 80-hour schedule and then give him the following week off, and at that he spends most of his time preparing, supervising, and then cleaning up from meals. Man, I gotta get me some bots!