Forunately, our plans for this year were to have a simple family dinner at home, with just my immediate family. I am pretty experienced making a typical Thanksgiving dinner, having done it about 6-8 times over the years. I don't make anything fancy, just stick to the basics. I am also fortunate that my family is totally not picky so there was no pressure on me.
I really only had to make a few changes to leave out the dairy and the gluten as follows:
Use GF bread for dressing (this was the biggest change by far and the only noticeable one)
Rub turkey with small amount of oil instead of butter for browning.
Thicken gravy with cornstarch instead of flour
Replace butter with Earth Balance in Sweet Potato Casserole.
Leave butter and milk out of mashed potatoes.
Everything turned out really well. The only problem was the dressing. It is typically my most favorite part and I always make it the same way, and the same way my mother made it, and the same way my grandmother made it... You get the drift. I think it turned out fine but definitely is no longer my favorite part of the meal. Fortunately the gravy was excellent and everyone knows that gravy covers a multitude of sins.