I've heard of many solutions over the years that I've read. Some guys like the idea of removing cars. I would always prefer not to handle them if possible. I guess it comes down to what you want, what you can afford, and how much space you have.
I like Christopher's idea of parking trains under the layout. Ed's go above which I had never thought of.
I have read of various types of drawers and track cassettes to solve this issue. I've even seen a type of elevator system that moves whole trains up and down. Your decision and choice of what's already been done, is totally yours. I would only suggest looking around (as if you haven't) before you settle on something that may end up taking away enjoyment of running.
Now having stuff on display is well worth the real estate it takes up. So I would say that glass display areas is always worth the effort. That especially comes handy when the layout gets younger visitors that like to grab everything in reach.
I have to admit that I know of some of your work, but nothing of what you are building now. So I apologize for the interruption. You are probably more into these trains than I am. I have attempted some failed layouts that I feel would have been better executed with some studying before hand.
BTW great looking work so far!!!