I grill zucchini or summer squash a lot. I've done slices of potato or sweet potato before too. I haven't tried it, but asparagus would probably work well. If you have a grill basket, you can do things like broccoli or cauliflower or green beans. Or look up cooking vegetables en papillote, which is cooking them enclosed in a parchment paper or foil pouch.
Or branch out and try new and different salads, especially if you like the make-ahead factor. Here's some ideas: http://meljoulwan.com/2019/04/23/15-paleo-side-salads/, https://whole30.com/whole30-recipes-salads/
