It was always a big hit at pot lucks and such, I'd get a couple of jars of the small jars of marinated artichokes (dump in the marinade, depending on the size you might need to cut the artichokes a bit), some nice bright sweet peppers in various colors (red, green, orange) cut in big chunks, a sweet onion again, cut large. A zucchini is nice in there as well as some fresh mushrooms (I buy presliced large ones). I just kept chopping up stuff until I filled the bowl, may need to add some additional Italian dressing. Make the day before/marinate over night. For crowds/fussy people I usually offer some crumbled feta on the side, or lately I've been using cotija.
A bruscetta sort of thing is always good, you don't need to have the toast just slice tomatoes into wedges, fresh basil cut into strips, black olives, onions (smaller chop). Dress with balsamic vinegar and olive oil, or a balsamic/red vinegar italian dressing. Marinate over night and save some fresh basil to sprinkle on a garnish.