I would suggest similar vegetables, like sturdy root vegetables (potatoes, butternut squash, carrots, parsnips, turnips, sweet potatoes). Celery can be roasted but it's so different in cellular structure to the other vegetables; I'd leave it out of this combination. Celery would be nice with onions, tomatoes and summer squash or zucchini.
3 important things: enough heat, enough room and consistent sizes. You want a hot pre-heated oven (425 degrees) and a large jelly roll type pan that the vegetables will fit on in a single layer. And they need to be cut into the same size pieces so they'll cook at the same rate.
Toss all the cut-up vegetables in a large bowl with just enough olive oil to lightly coat them. They shouldn't be dripping in oil, and you don't want so much oil that it's pooling at the bottom of the bowl. Salt and freshly ground black pepper are all you need at the beginning. Taste a raw vegetable for salt and pepper and add more if necessary. Don't be too skimpy on the seasoning.
Roast them until they're very tender and quite golden brown. Stir them around a couple of times during the roasting so all sides get brown. The nice caramel color will mean they'll taste delicious. When they're done and still very hot, sprinkle over them: a couple of tablespoons of finely chopped thyme leaves and oregano leaves (fresh), and just a spritz (a half teaspoon or a teaspoon) of good quality red wine vinegar. Toss everything together.