I won't recommend any of the top places with multi-star ratings, because they're already heavily reviewed all over the Web. Perhaps I can suggest a couple simpler options, only one of which addresses Thanksgiving, and then only glancingly.
Antica Pesa on via Garibaldi in Trastevere is a nice restaurant with excellent food that won't disappoint you.
Cacio e Pepe is a simple trattoria on via Avezzana (in the Prati neighborhood) that makes a wonderful gnocchi alla Sorrentina, but only on Thursdays. It's a tiny place with very good simple food.
Near the Piazza Barberini on via degli Avignonesi 34 is a fine place for all your dining needs (well, two meals a day, at least): Gioia Mia (aka Pisciapiano) is a small trattoria with a wood fired oven that makes highly enjoyable Roman classics. And the pizza's not bad, either. I go every time I'm in Rome. It's closed Sundays.
You will not regret Gelarmony for wonderful Sicilian gelato on via Marcantonio Colonna 34, near the Lepanto Metro stop.
Buon viaggio.