In the Star Fleet Battles universe, civilian ships are very utilitarian. Here are four examples: Bulk freighters: http://www.starfleetgames.com/images/Mongoose/Starline 2500/General/Small_Freighter_1_-above.jpg http://www.starfleetgames.com/images/Mongoose/Starline 2500/General/Large_Freighter-1_-_above_F.jpg There are three- and four-pod designs as well. Smaller trading vessel and priority transport: http://www.starfleetgames.com/images/Mongoose/Starline 2500/General/Free_Trader_2_-_above.jpg http://www.starfleetgames.com/images/Mongoose/Starline 2500/General/APT_with_drone_ports.jpg
Makes sense to me. I'd also expect them to be at least of generations behind the top-line standard in drive systems, computers etc. Let the bureaucracy sort out the kinks first. For instance, I liked that Xhosa had old "movie era" LCARS panels rather than the modern ones on the hero-ships, her transporter was also outdated and unreliable IIRC.
Forbin made an awesome freighter a few years ago. I hope he doesn't mind me posting a link to it, personally I do like it a lot. http://www.inpayne.com/models/kitbash/trekpage_fitz.html
Here's my contribution the Starstream Yacht. You can find the plans booklet it on my deviant art page.
Here is a Quickie... The Federation Oscar Mayer Wienercraft: Direct Link: https://i.postimg.cc/RFd33Ctt/Concept-Federation-Wienercraft-00.jpg