I'm thankful for my in-laws.
(I know - you don't hear that too often right?)
My mother-in-law, Nancy, is a bit nutty but in the best way possible. She goes above and beyond for every member of the family, even for my parents, Grandma and brother. (Please recall Hurricane Ike and the Lowe-Turner co-habitation.) She makes sure we have everything we need and most things we want, even if the requests are a little ridiculous sometimes.
My father-in-law, Jack, is the absent-minded professor. He's one of the few people who is both smart and wise. He's book smart like nobody's business but also wise in that he knows when to give his two cents, when to pick his battles and gives outstanding marital advice. ("Ross, you get one, she gets two. This is how this works.")
My sister-in-law, Meg, is the sister-in-law jackpot. While she made me cry (happy tears) at my bridal shower, most times she leaves me doubling over laughing. She totally gets me...and usually she takes my side in debates which I also really appreciate.
And none of them take themselves too seriously which makes (gentle) in-law joking and teasing that much more fun because they lead the charge.