My original plan was much like yours, containing only enterprises and whole models. I wanted mine to scale (unlike the enterprise E). I changed my mind both after realizing that a glass display case was expensive as the dickens and mounting whole models on the wall would be tricky, and maybe not look so good. I started adding a few ships I liked and soon I had ordered $150 worth of models off of Ebay.
You have to consider that on the Ent-D the models were closer to a 1/1000 scale, and a 1/2500 scale version would be maybe about 18" by 18". I believe AMT will soon be re-releasing a 1/1400 Ent-C. Combined with the 1/1400 D, and E. And the 1/1000 B,A,Original, and NX. would make a pretty large wall, but of course not be quite to scale.
As for a 1/2500 wall, F-toys has several models in the 1/2500 scale, including the Defiant an the NX-O1. I've only been able to find these on Ebay, and the shipping is a bit high unless you order them in bulk. Furuta has a few ships near to scale +/- %10 which are fairly cheap such as the Grissom, Prometheus, and Voyager. I don't consider it a big deal because on the show the mess around with the scales so much anyhow. I'm converting several ships such as the Reliant, New Orleans Class, Stargazer, Nebula, Centaur, Equinox, Soyuz, and Cheyenne Class from assorted enterprises, (as the show's model makers did) but I am a pretty decent sculptor. If your feeling bold there is also an old DS9 model that is listed as 1/2500, but AMT exagerates scales more than I do, as a bonus it comes with a runabout about the size of a bee. My original plan was to convert a Polar lights 1/1000 NX class into an Akira, but once I was holding it in my hand and remembered how much modelling putty cost I changed my mind and forked out for a pricey resin one.
As for gold plating, I've looked into it. And unless you wanna fork out serious dough I wouldnt go down that road.
Cheers
John