In general I tend to put the firmer veggies (potato, sweet potato, pumpkin, red onion, leeks, parsnip, carrot, etc.) in one dish, and softer veggies (zucchini, eggplant, yellow squash, mushrooms, red peppers, tiny toms, etc.) in another dish. I do this because the softer veggies will release a little more steam whilst cooking and I don't want to "wet" my firmer veggies too much ... but I cook them for exactly the same amount of time as I like my veggies "caramelised" which gives them such a yummy flavour. Often I won't have enough to do two trays, so I will put them all together in one (especially when I am trying to use up "bits") and that is fine too.
I will also add green apples and green pears to the veggies if I have them on hand ... I don't peel them, just cut them into quarters and core them ... they add a delicious sweetness, and in particular the pears hold their shape so look lovely on the plate, whereas sometimes the apple may break in two but still delicious.
Once baked I cover my trays in Alfoil and allow the veggies to "rest" for 10 minutes before uncovering ... this allows steam to temper the little caramel bits on the veggies making them deliciously soft ... and even more yummy! Once the veggies are uncovered, that is when I will dress them with whatever I want (extra olive oil, sea salt flakes, pesto loosened with extra olive oil, balsamic glaze, fresh herbs of choice, etc.).