I have a pasta salad recipe that can be made with or without chicken. It's substantial enough to be a meal, or even just a side salad. Can be made the day before. Let me know if you're interested in the recipe and I can send to you.
Otherwise, you can make a crudite bar, with different dips, veggies, pita, hummus, etc.
Costco has these amazing veggie burgers that unlike traditional soy burgers that are meant to taste/ feel like meat, these are actually meant to really be *veggie* burgers. I know that probably sounds gross, but I sampled one, and they are so good! You can see the pieces of real red pepper, etc. in them, and they have this sweet and crispy taste and texture. You could always serve them as a "burger."