Garlic, lemon, salt, pepper and olive oil for most, sometimes I add crushed red chilis. For potatoes I switch out the lemon for rosemary.

Roasted vegetables develop such a wonderful taste that I add very little if any spice at all. For instance:

Zucchini - just olive oil and salt

Butternut squash - olive oil, salt and minced garlic

Eggplant is an exception. I don't peel it (the skin is the best tasting part of it). I slice it lengthwise, sprinkle a lot of salt, leave for about an hour, wash, squeeze, toss with oil, roast. Once it's roasted, I cube the slices and pour on them a hottish sauce of fried garlic, crushed hot pepper and cumin, with some vinegar added at the end. Delicious hot and even better cold from the fridge the day after.

I mostly just use salt and pepper. I like the pure flavor of the vegetables.

I often use rosemary, garlic and olive oil for more than just potatoes. Your spice and herb combinations sound really good. Like wintercat, I'll often finish the veg in something so that the items don't burn like a bit of flavored olive oil (lemon, garlic, etc) near the end.

There's a Greek blend called Cavender's that I really like on roasted veggies. It comes in a salt-free version too.

I love roasted cauliflower with olive oil and Madras curry powder.

I love Spike Veg-It on roasted potatoes and a roasted broccoli, cauliflower, carrot & pasta blend. Also good on homemade French Fries.

Cavender's is a great balanced seasoning. Haven't tried it on veggies (need to after reading cookebook's endorsement) but love it on chicken and hamburger steak.

I use Za-atar and store it in the freezer because it contains sesame seeds. Sometimes I just use ground sumac. My other often used blend is Cajun seasoning, which contains oregano, basil, thyme, garlic powder, onion powder, cayenne, black pepper, and salt.

I have a small jar of nutmeg that I use a Microplane with instead of a nutmeg grinder, but I seldom use it for anything other than desserts of eggnog. I especially do not like nutmeg on spinach, but on parsnips it might be good. I also keep Furikake on hand for Japanese dishes.

Drizzle with olive oil then toss with salt and:

...Smoked Spanish paprika on butternut squash

...Chipotle powder on sweet potato "fries"

...fresh rosemary on red or Yukon gold potatoes

...fresh rosemary on carrot "fries"

...just salt on green beans

All your ideas are very interesting.

Wintercat, your eggplant sauce sounds fantastic!!

The parsnips with nutmeg and mustard are going on the Thanksgiving menu. Still toe curling good out of the fridge. I put them all out cold for lunch but kept picking at the bowls and had had my fill before I even sat down. :)

We were just playing around, but I do think that seasoning--with just herbs and spaces...doesn't have to be salt and pepper--does bring out the flavor of the vegetables. The parsnips--and I was very generous with the nutmeg--taste like a "dish" rather than just parsnips. The others taste exactly like themselves but just a bit moreso, the same way they would if they had exactly the right amount of salt (not enough to taste salty, not so little as to taste flat), and we used about the same amounts as you might of S&P.