After that, all sorts - from golden age sf through more modern stuff!  The universe is your oyster.

Heinlein for 'detail' of what future might be with some Traveller tech, Asimov for bigger picture stuff, Feintuch for claustrophobic military feel, Bjork 's Serrano and Vatta series for good small ship stuff.  Poul Anderson 's Flandry series for merchant trading, and of course EC Tubb 's Dumarest series for real classic Traveller difficult travel atmosphere. 

At the moment I'm on a generation starship reading jag so devouring classics like Aldiss' Non-stop ('Starship' in the US), Heinlein's Orphans of the Sky and Harrison's Captive Universe - you must read all three! But newer things too like Sterling's short story Taklamakan,  and novels like The Clockwork Rocketship (with really alien aliens and a whole alternative physics!) and more earth based things like Baxter's Flood.  Hull Three Zero by Bear I found way too dark and weird. 

This last project has been interesting though because instead of reading favourite authors and we'll trodden paths, I've been reading around a theme which has extended my range and given a great insight into how different authors have tackled a similar subject.

hth

tc