How far ahead to make...

root vegetabls? Can I make night before then reheat? Chop night before (I'm guessing no)

What about mashed sweet potatoes?

Re: How far ahead to make...

I am a big fan of preparing dishes ahead, especially for a large gathering or holiday. So I always do stuff ahead of time.

The mashed sweet potatoes -- you definitely can do in advance (assuming you are serving them as sort of a baked casserole dish). I have a recipe for maple pecan baked sweet potatoes... I make it a day in advance. I bake the potatoes, mash them, add the milk, maple syrup, top with pecans and marshmellows, etc. -- I basically assemble the entire dish -- then I cover it and stick it in the fridge. I just bake it in the oven right before serving.

The root vegetables - how are you serving them? Assuming you are simply roasting them, then no, I wouldn't make them ahead and reheat. I think they'd be too mushy. But I would cut them ahead of time and put them in airtight containers, like ziplocks or tupperware. Then, just toss with oil and seasonings and stick them in the oven when you are ready to make that dish. Cutting the vegetables is really the only labor-intensive part, so as long as you do that earlier, you should be fine.