I don't think the annual free night is worth the annual fee, not compared to priceline. You can only use it on categories 1-5 and only in a six month window. This was a better deal a few years ago, but Marriott keeps making the categories more devalued. I'd cancel my card but for a good balance transfer deal I got on it quite a while ago.
The best thing about MR is the travel packages-and even then, you need to stay a week on one place. Really, SPG is a better value, especially if you play the miles game. And Hyatt-when you can find them around, might be the best for nice hotels with their usually good promotions.
Though Priority Club-though it doesn't have as many nice hotels as Marriott, IMO-is really the best for free nights.