I'd say do a few things really well rather than lots of variety.
Think about how much space you have on your bbq and plan accordingly.
I find skewers tend to go down well.
I'd do tandoori chicken and pepper and red onion
Lemon and garlic prawns,
Haloumi with pepper and courgette (drizzle haloumi with honey)
Really nice with flat breads or pitas just flashed on the bbq
Then I'd do some beef burger with nice rolls and all the add ons, sliced red onion, shredded lettuce, sliced tomatoes, gherkins, relish, mayo, a choice of cheddar or blue cheese that can be melted on.
I'd do a homemade apple coleslaw, sweet potato salad, roasted veg cous cous, a Greek salad, green salad and a plate of sliced tomatoes with mozzarella, basil and slivers of red onion, drizzled with balsamic, plenty of salt and black pepper.