With its free frader crews counting every credit, its technologically minimaxed mercenaries and its general Space 1977 feel Traveller seems a very bad match for Vancean SF to me.
For a start the Oikumene/Gaean Reach settings are really one loose confederation with no military to speak of (although there are interstellar police forces that sound rather more Scout- than Navy-like) - so you're not going to find the standard CT chargen system much use.
Traveller random UWP's are also incapable of expressing the sheer weirdness of Vance's societies - or that his inhabited planets are all very earth-like in terms of atmosphere, gravity etc (though not flora and fauna which is as weird as his societies).
In the end Vance is just not interested in the hard-SF, high-tech stuff that Traveller obsesses on and his starships, computers, rayguns etc are purely 'speed of plot' devices which have no value other than to put the characters where he needs them to be.
If I had time to adapt it my own rules choice would be the Dying Earth RPG with starships treated pretty like magician's manses (i.e. they are largely abstract offstage entities that allow the owner certain benefits), an abstract wealth system, very little emphasis on military hardware and combat and a focus on social interaction.
Heroquest (another Robin Laws system) could also do the job if the generic Questworlds version with SF rules ever actuallty comes out.
Haven't played it yet but from what I've seen of the rules the Serenity RPG probably would also be a closer match to Vance's SF than any version of Traveller.
The point being that to represent Vance's fiction properly you need a system that allows you to play out the stuff that an RPG like Traveller would have to abstract - and which abstracts the stuff that Traveller insists on you playing through in gruesome detail.