If you're looking for a challenging Thanksgiving Day race (longer than a 5k), check out Highland Park. This pretty competitive, "small" (approx 1,000 10k participants) race has some decent rollers with a moderate climb to the finish line. It's a large loop around the neighborhood of Highland Park. The course is well-marked with 2 aid stations along the way. Post race pies and coffee or hot chocolate really set the holiday mood. It starts at 730 (5k) and 810 (10k) so you can get home in plenty of time to make stuffing or whatever :)
This was my first 10k ever and it was quickly evident I have no idea how to manage this distance. Going out like a 5k is not recommended. I had to pull off to the side of the course to dry-heave a couple times (lactic threshold) but managed to get back and finish decently strong. I'm VERY excited to give this distance another "go" next year!
Happy holidays, all!!