For my friend's hubby's bday party, I used the following veggies:
baby carrots, red new potatoes, zucchini and squash from the garden, yellow onion and garlic.
You can seriously use whatever you have on hand. Roasting your vegetables gives them such a rich flavor that you lose when you steam or boil. Some of my other favorites to roast are:
sweet potatoes, yams, parsnips (don't knock 'em till you try 'em), brussel sprouts and cabbage.
Rinse and chop your veggies and onion so that the chopped pieces are relatively uniform in size (you want them all to cook for the same amount of time). Lay them all out in a 9x13 pan. Drizzle with a generous amount of EVOO (Extra Virgin Olive Oil). Don't be stingy with this. Season well with course salt, and add 3-4 whole peeled cloves of garlic. Add several (4-6) sprigs of Rosemary. Toss the veggies to ensure that they are all well coated in the EVOO.
Bake at 425 for approximately 25-30 minutes. Pull them out to flip over with a spatula half way through. You will get some crispy ends, but you don't want any of the veggies to burn. Once a fork goes easily through, the veggies are done! You may opt to pull the whole garlic cloves out, but they are actually much less potent when they have been roasted so I leave mine in.