"It wouldn't be hard to get lost in space if your travelers did not have access to relatively sophisticated astronomical equipment. One would have to be able to track things like quasars and such to get a "bearing" after you lost sight of your local stellar neighborhood. But we're talking hundreds of light years away from home (at least)."

The idea would be that nobody would be conscious (suspension, etc), and certain efforts would have been put into the engineering of the craft to dump records of course, deration, speed etc upon arrival to a suitable system.

Furthormore, if one assumes functional AI, then one could posit that historical and encyclopedic references could be scoured (the process going on for the 100s of years the voyage takes, even). Size of the planet, spectrum, etc. Yes, that could all be reverse-engineered from human and terran biology within a very narrow field... but in any sphere of space of, say, 1000 ly... probably several hundred stars will fit within that range.

And you have to assume Sol exists in the night sky to look for ;-)

"As for drive plumes, just invent a drive without plumes. Patent pending."

But it has to sound plausible... thats the hard part. I don't like the 'dune' style where you wave your hand and POOF! magical technology appears.