Babylon 5, the gates provide access to hyperspace, where physical travel once in there corresponds to a larger area in real space.
the theory used in David Feintuchs : Hope series of novels, where no views of outside can be gained whilst the drive engines are on with real space objects like suns and planets possible to be struck.
there are the "folding space" drives, almost instantaneous transfer from one area of the universe to another, based on numerous theories, normal one being two identical areas of space.
then the Einstein theorised drives, where you can go no faster than light speed and the closer you get to light speed the slower time passes onboard. go 5,000 light years in one year shipboard, return and find earths populations have aged 10,000 years!
personally i'd like to write around folding space type drives, to keep continuance of time zones and characters. if you read Poul Andersons : Starfarers you end up with main characters on board such a voyage and the generations upon generations of living, breathing and dying earth peoples and the cultures/politics and sentiments they go through that will not matter to the explorers once they are back as they will be so great that civilization will have utterly changed and be unfathomable to them.
many times you find stories with generation ships sent out to the nearest stars at quarter light speeds, only to find that 100 years later they are arriving to find colonies all setup by unrecognisable earth cultures who on progressing to faster drives, jumped ahead of them.
it all depends on personal preference, audience and whether you have any definitive scientific beliefs in specific methods of star travel
