making Shish Kebabs for easter... advice?

[AustinChief]

ok, here is the plan...

Take a few lbs of top sirloin cut into cubes and marinated in a garlic-mint-yoghurt sauce overnight... make skewers of sirloin and also make skewers of various veggies

Grill.

Serve with pita bread(people can mix match veggies/meat as they please) and 3 possible sauces
White Sauce- garlic-cucumber yoghurt sauce
Red Sauce- Chili sauce with a touch of garlic and tomato
Orange Sauce- garlic, red pepper, paprika, tomato, almonds, bread, red wine vingar & olive oil pureed


OK, now here is where I need advice... is top sirloin my best bet for the meat?

What are the best veggies to use? I am thinking now of onion, tomato, various bell peppers, various mild to medium peppers (Anaheim to Jalapeno), zuchinni, mushrooms... anything missing?

Any advice helps...