The next panel I saw at the Tucson Festival of Books was Space Travel and Spacefaring Societies, with Catherine Wells, John Vornholt, Timothy Zahn, and David Weber. Again, me attending the panel reflects an interest in a topic more than an endorsement of the authors (though I am reading one of Wells' novels right now--the middle book in a series, I think?--and find it interesting and a surprisingly good use of omniscient POV).
If you're particularly interested, an audio recording of the whole panel appears to be up at Bloomsite . Since that's available, and since I'm tired tonight, I'll just hit a few things I noted. The panel kind of wandered, so there was talk about technology, but not so much about space travel or spacefaring societies!
David Weber made a good point that boiled down to, humans are going to keep doing the same things they've always done, but technology lets us do more of it, faster.
As for actual talk about space travel, Catherine Wells discussed tesseracts and wormholes (real wormholes being the size of a pinhole, but you need an excuse). She suggested you hint at technology but don't get into details.
Timothy Zahn said that you could use any drive with any name (even "Fred's Transport System") to get from here to there, but the limits and constraints must be clear to play fair with readers.
David Weber said that before starting a novel, he writes an essay laying out the universe, including what's in their technology toolbox. He said you must include limits and understand the logical implications of any changes you make to the system. For instance, we need an economic reason to go into space before we will do so. And faced with the NEED to do it, we will find medical and technological advances to help us through space travel. All technology used in telling a story is a plot device, and if it is not used to push the story forward, it's a weak story. Weber also makes an interesting argument (more than once during the festival!) that science fiction stories for modern societies are like fairy tales in a non-technological society.
Zahn and Weber both mentioned "Threat evokes response." Zahn noted that once technology is out of the bottle, you can't stuff it back in. But he suggested that you can hand-wave away technology problems when you assume there's a better mouse. In other words, logically, airplanes might be piloted by drones if the technology existed, but if you want humans in the planes, then create jammers so that the droids can't function.
And my notes failed me here but one of them said that the best way to convey future societies is don't call attention to them at all.