I also think a good thought-experiment when it comes to this sort of thing does not include numbers-pulled-out-of-a-hat (subject to change as plot requires and begs the question "you crunched the numbers?"), or descriptions of physical appearance (really, there's only one configuration?).
No, instead give a general description of how it works, but the meat should be an exploration of the implications the new tech/science/capability has on the universe (cultural, social, economic, political, etc..)
Although this isn't as bad as when fans "design" ships (bleh, like just throwing together a picture to satisfy individual aesthetic desires is really "designing") and in a desperate attempt to make their creation "special" they say "it has advanced this and that." RIght, because it's going to be any more advanced than the rest of the stuff coming off the production lines in the same time period.
I'd like to see further development of the ship concepts at the back of the TNG Technical Manual
. I really liked the idea for the one that was a forward section with two warp nacelles and mission-specific modules mounted aft along a spine. The book suggests that they aren't quite at the point where they can make that arrangement work yet, but it's very interesting to think how the Starfleet might begin to look if they reach a point where the tradeoff for the lousy warp dynamics becomes acceptable.
(Frankly, I just thought the little top-down view of it looked cool as well, which is an achievement considering the design principles it employed and the expectations we've got for Starfleet ships. I'd love to see some good artist work up more about it.)
A related concept ship in there had a primary hull made of replaceable segments, adaptable for different mission profiles. This gave it a "chunky" look echoed in some fan designs.
The giant everything-and-two-redundant-kitchen-sink ships would still be the ones you'd want to send off on the really long-range and long-term space probe missions, but for ships operating within the Federation, this large-scale application of modularity offers many advantages. I wonder: would crews start to be assigned to modules and not to ships per se?