You may want to post this in the Home Decorating forum here as this forum is more about the nuts and bolts of windows and doors.

The window trim change would be to Craftsman style. Unless you are doing the work yourself it seems a lot of expense for little difference on upstairs windows. It would, however, be extremely easy to do on your front door as you would only need to change the top board. And you could replace the side lights with solid wood inserts, or you could use textured glass that would obscure the view while still letting light in. While the limestone exterior is very light it has a yellow hue. Simply speaking the easiest way to find colors that work with the warm limestone is to choose a nearby color. That was probably why the trim is green. Since you prefer a modern look, I suggest you keep your siding light and use color only in the trim. Below are two combinations that I like. I darkened the roof color in these pictures.

I like the way this house is finished with simple cove crown molding. I like that the molding is white, but the door is stained wood. Where the ceiling is slanted they omitted the crown molding; much cleaner look for that area. The base molding is quite generous.

I love the sage green trim around the lighter front door, RL Location!!! I guess I like the green and brown as those are the colours of my Dad's house in Maine and it looks so great in its surroundings. Classic is classic for a reason! I think the green trim would really complement everything. Sorry about the windows. I hope you didn't find my comment insulting as I didn't mean it that way. There are pains and stains for vinyl windows, btw, but I've never used them so no experience.