Yeah, the main reason I suggest roast chicken first is because it *forces* them to think of grilling in a whole new way. Like Craig, I find that-- even when they are eating kettle-roasted meat-- people just can't grok that grilling doesn't need to be thin pieces of food right over heat. So I just tell my padawans, "Go and cook some chickens-- then come back to me and we will talk". And most of the time, a simple roast chicken is about 1 chimney of coals for about 1 hour. Pretty foolproof.
Unfortunately, tri-tip is practically nonexistent out east (in my experience, anyway-- I need to find out where Chris is getting his!). But chuck roast or pork loin is another good idea. I think I'll start suggesting ribs to people, since they take a relatively short time and have a big payoff.
And Chris, that spatchcocked chicken is a thing of beauty. I am inspired. (I picked up a Jacques Pepin cookbook on clearance the other day, and followed his instructions for de-boning a whole chicken. It went pretty smoothly, and got me thinking about boning out a whole bird, then stuffing it and tying it back together to go on the rotisserie...)