Personally, i'd like to see pictures of the USS Universe from DRG3's Serpents Among the Ruins, and Cleopatra's Needle, the civilian ship that Picard used in Christopher Bennett's The Buried Age.
I imagined Cleo's Needle
as looking kind of like the rocketships in '50s movies like Destination Moon
-- really long and sleek and cylindrical, fairly simple in design.
I think the ship seen in this video from about 2.00 would be a good start at least. It probably isn't sleek and simple enough as is to fit the description, but I really like the basic design. Redesign it a bit and it could be a ship that is a combination of classic Starfleet and a Vulcan ring-ship.