pocket bread
gyro meat
falafel balls
tomatoes (for sandwiches)
onions (for sandwiches)
tzatziki (for sandwiches)

hummus
pita chips

greek olives
spanikopita triangles
greek salad
baklava triangles

pocket bread- 1 whole per person
gyro meat - 1 pound per 3-4 (how big of eaters are they?)
falafel balls- almost everyone will have some, 4 per person, probably none left
tomatoes (for sandwiches)- about 10 pounds per 100, a little more if sliced instead of diced
onions (for sandwiches)- about 7 pounds per 100

tzatziki (for sandwiches) people will also use for salad and just dipping. Allow at least 1 cup per 4.

hummus-1 cup per 4. Don't just treat as a dip; do the presentation where it is spread on the tray, spoon-scaled and dressed with olive oil and sumac.
pita chips-1 pound per 15

A simple and handsome addition would be the canned vegetarian stuffed grape leaves. I prefer Aetna or Aegean brand and allow 5 cans per 200, which is 300 rolls.

greek olives- 1 gallon per 100 if no olives in the salad, 2-3 quarts if olives elsewhere.
spanikopita triangles= 2 per person
greek salad- use the Greek village salad recipe amounts on this site, can be made ahead except any lettuce

baklava triangles- self serving, if the baklava is cut in small pieces, people easily eat 2-3 each. You need coffee with this- see dinner coffee on the beverage planning page, a nice French roast.