We've touched on this issue before, but it seems to me the clearest, most obvious way in which a particular incarnation of Star Trek demonstrates its character is via its ship (or lack thereof).
Kirk's Enterprise meant business:
It was light, fast, and just looked like it packed a punch. I think it's that sort of industrial quality, much like a navy vessel. An even better comparison might be a submarine, which, after all, is what Trek starships are at heart. This ship was suited perfectly to The Original Series. You get the sense that Starfleet is really just a fledgling organization trying to establish a foothold in the galaxy, yet one with determination and firepower. Things aren't perfect yet, but they have potential, if only Kirk and other adventurers like him can build Starfleet into a real force for change.
The ship underwent a major refit for The Motion Picture which built on the principles established by its predecessor:
The Enterprise got slightly bigger, all the elements thickening up a bit to make it look a little sturdier. It looks tougher and more impressive. By this time Starfleet has carved out a niche for itself. It is expanding by leaps and bounds, and other races like the Klingons are being forced to realize they must take the Federation seriously.
Follow this line of development for 70 years or so and you end up with Picard's Enterprise-D:
Picard commands his Enterprise at the height of the Federation's power and technology. It is massive, over 2000ft. long and incorporates the best Starfleet has to offer at every turn. It's like a luxury liner compared to Kirk's Enterprise and even has massive quarters where crewmen can house their families. It can still move and kick butt, though. In fact, to a much, much greater degree than Kirk's ever could, but it's not meant to. It's meant to inspire awe as it patrols the provinces.
Compare the development of the U.S. Navy submarine from the 40s 'til today:
|Then - An emerging political power.|
|Now - A bloated economic empire.|
One of the first ships to be developed after the introduction of the Borg threat, the E looks like it's ready for war. Bigger even than the D, it's long, lean, and mean. Everything got stretched out so that it looks like it's moving fast standing still. The engines just keep on going. Like before with the original Enterprise refit, everything has been tightened up and brought in closer to make it seem stronger. I’m just saying. It looks like it might just flip its shit and totally tear you a new one at any moment.
Let's compare the two bridges:
The Enterprise-D bridge is plush and arty. It's designed for negotiating and research and other B.S. The Enterprise-E bridge on the other hand...
...is designed for battle.
Next up: the Trek Civil War that should have been.