So FiveThirtyEight has this article on what sides and desserts people in different parts of the country prefer for Thanksgiving. As a kid I sometimes ate at my grandmother's house, but as an adult we developed a Thanksgiving tradition with relatives in Miami (and my aunts' friends) which we've partially transferred to my cousin's in Colorado after my aunt refused to host this year.
With sides, the two things that struck me were the Southeast's love for canned cranberry sauce and the Northeast's love of squash. My aunt's longterm boyfriend makes a cranberry sauce with two kinds of canned cranberries, pineapple, and pecans. I don't like it, but when I made fresh cranberry sauce nobody ate it except me. I don't like squash, but my mother brought a butternut squash to Florida every year so people could have proper squash instead of yams, which seems to be the non-New England equivalent. We're not involved in the sides this year, so it will be interesting to see what they have. Mashed potatoes and gravy also seem like an essential Thanksgiving side, though I don't like them.
Another thing that stuck out to me is that apple, pecan, and cherry pie all seem like essential Thanksgiving pies, but sweet potato pie seems kind of redundant for pumpkin pie. Sadly, we never do cherry pie, usually because my mother insists that five kinds of pie is enough (it's Thanksgiving, Mom!) and vetoes it every time I suggest it. This year she didn't veto it, however I told my cousin and his wife I could make cherry pie and key lime pie if they found key lime juice and canned or frozen cherries; my cousin's wife found the juice but not the cherries. Don't know if she couldn't find them or they just didn't want cherry pie.
This year we're not doing pumpkin pie (I assume someone else will bring it) but are doing apple pie, pecan pie, Tollhouse cookie pie, and key lime pie, all of which we've developed a reputation for. (My brother has special recipes for pecan and cookie pies, I have one for key lime, and we use Northern Spy apples for our apple pie, which you can't get in most of the country.)
Also, in Miami I was the only person who insisted on having a turkey leg, it will be interesting to see if the same pattern holds in Colorado and I'm a little worried.