The Alternity Starships book suffers, from a Traveller POV, from a bit too much of the "Flash Gordon" effect. Really odd structures, a shifting deck scale, and very odd technology makes a numnber of the deckplans a starting point, but not a lot else.
Slightly better, but a bit harder to find, would be the book "Stock Ships" for the original (D6) version of the Star Wars RPG. (Note that either the Shatterzone or SpaceMaster games had a book by the same name that is absolutely useless, so be careful if you web-shop).
The (very) occasional appearance of deckplans for D20 Star Wars can also be useful. They are few and far between, though.
Based on the examples I've seen, the deckplans so far published for DragonStar are worthless for Traveller except as wierd alien artefacts found floating in space.
Two sets of deckplans published for the Fading Suns setting are also "Approved for use with Traveller." As long as you assume the fuel is on a deck "not depicted" and that all marines/ship troops can sleep in their chairs for the whole trip, these might be vaguely useful...
SJG's GURPS: Traveller efforts (and the Classic Reprints) aside, the web is your best bet at the moment until Hunter decides to do his own version of Traders and Gunboats...