Re: I have appetizer writer's block
For picnics, I like to do stuff on skewers. There's the tom/basil/mozz like you already said, but there is also chorizo/manchego/grape as well as feta/tomato/cucumber/black olive.
I also like to do break chunks on skewer with a leaf of mint or basil and either brie cheese slice or prosciutto.
They are all prep ahead, and you are just cutting and assembling. I did an entire party's worth in 90 minutes of naptime prep.