You'd be surprised on both accounts there I think.
UV mapping vents and other small details is quite easy. Just select the faces that your larger scale UV projections didn't capture properly, find a camera angle that
will display the whole of them and project from view again. Repeat until all details are decently mapped.
And you no longer *need* bold textures to bring out details on stuff thanks to shine maps. Certainly good maps are still very very important, but the shine maps will basically illuminate the geometric details, like this:
The textures there were from the original Loki, and as such are very low res and blurred, yet you can still pretty clearly see the details.
Bottom line: Add as much detail as you _need_ to get the ship looking as you had envisaged (within reason).