The company and the venue are the most important things. Everything else is just icing.
My favorite traditional picnic fare (that my family has eaten many times over the years):
Individual French bread loaves with a variety of sliced meats (ham, roast beef and turkey) with sliced cheddar and swiss cheese, mayo and mustard, sliced onions, sliced tomatoes and lettuce (all to be assembled as you like).
Potato salad (preferably home made)
Pickles (Bubbie’s Kosher dills)
2 kinds of potato chips (one of the rare times any of us ever eat them) and we switch these up: salt and vinegar, barbecue, Maui sweet onion Kettle chips, or the regular big chips with ridges (but only if I’ve made onion dip to go with them).
Lemonade and Iced Tea
And chocolate chip cookies or brownies (always home made) for dessert.
A couple of years ago, my brother and I went to a pumpkin patch out in the country and I made these awesome sandwiches (which I knew he would love and everyone else would be wary of) I used focaccia bread from Trader Joes and put sliced fresh mozzarella inside with arugula and a spread of pesto and some chopped up sundried tomatoes. They were heavenly. And I think we both had orange crush in a bottle to drink (a happy childhood memory drink, that we rarely drink now, cause it’s not very good for you, buy hey, it’s only once a year).
And me and my best friend (who is also a vegetarian) we have made cute little fake meat and cheese sandwiches with Yves brand fake boloney on little dinner roll sized buns (usually something super-healthy and whole grain). Then we’ll get a bag of whatever is new and healthy at Trader Joe’s. Could be black bean chips, could be seaweed crackers, could be sweet potato chips. Then we’ll get some bottled unsweetened ice tea, something like snapple or something from Henry’s or Trader Joe’s or one of those “healthy” stores. And maybe a vegan peanut butter cookie for dessert.