I think you have some good suggestions listed. If you're borderline zone 7, you want to find zone 5 grasses to winter over in a container...unless you can give them extra protection.

Phalaris Strawberries and Cream would be a great container selection. Nowhere for it to run. :) Use it by itself not in a mixed container. Zone 4

Chasmanthium isn't often used, but makes a very nice container grass in a shaded location. Zone 4

Both Sesleria autumnalis and cearulea would do well. Zone 4.

I'd recommend Carex Evergold, Carex Kaga Nashiki, & Carex Bowles Golden, all zone 5 and all with great color/variegation. Most of the wiry copper sedges aren't going to be much hardier than zone 6/7. You'd have a tougher time over-wintering those containers.

Here's a picture I found of Chasmanthium in a container at Blustem Nursery. I like it very much, especially used with other containers that provide color.

Here is a link that might be useful: