Everyone has their favourite ship class in this game. (For me, it's the Nova Class and the NX Class). However, currently unless your favourite ship is a Tier 5 (Soon to be tier 6?) ship, then you're forced to abandon it after you've finished the leveling curve.
However, recently cryptic have added ship weapons that scale (The phaser banks from the TOS enterprise, or granted by one of the featured episodes). Personally I think this is an awesome feature, but I would like to see it taken up one level. I think that if I aquire a Nova Class ship, and like it, I should be allowed to keep it all the way up to Vice Admiral and beyond.
I know the design team put a LOT of work into these ships and it's a shame to see them go to waste just because they are "lowbie" gear.
What I'd imagine, is taking the Miranda class for example, is that once you hit Lieutenant Commander, your ship automatically gets an extra engineering officer slot, and extra engineering console (Remember, Miranda is a cruiser), and maybe an extra weapon slot in the rear, then when you hit commander, it again upgrades to Commander level cruiser.
I certainly would love it if my favourite ship types were viable at higher levels. And instead of 3/4 choices, there'd be 9 or more choices. I think, of course, that each ship should have it's own strenghs and weaknesses at VA, but over all, the player should be able to use a lower level class if they prefer that class.