As I said, my broader visual look is Tom Clancy techno-thriller, and specifically the movie of The Hunt For Red October (Red Storm Rising not being made into a movie alas). In my mind's eye, there's very little "sci-fi-ness", e.g. no goofy outfits, no winged ships, no Star Trek-style aliens, etc.. I picture the insides of the ships like today's nuclear submarines, the uniforms straight out the US Navy (except for the digi-camo Working Uniform, but that actually might be kinda cool for the Honorverse).
Now, I would accept other visual looks. Babylon 5 has been mentioned. That would be an exelllent example to follow, especially the humans' Earth Force ships and uniforms. Another series that would be good is the new Battlestar Galactica.
For something a bit "outside the box", and the one videogame style I'd use, would be the computer game Homeworld. It's visual look was directly inspired by the works of artist Peter Elson, which were prominently featured in Stewart Cowley's Terran Trade Auhtority books (you can add the works of Chris Foss too if you want). I'd think that'd be an awesome style to use--lots of brightly-colored ships and bold colorful space backgrounds--and a lot more visually appealing than boring old white ships in black space. Sometimes I find myself drifting to this look when reading the books.
Yes, it's been said that Honor is Hornblower in space, but do you actually picture the Honorverse as the early 1800's Napoleonic era? Do you want the movie looking like Amadeus? Probably not
