For the past few years, I've noticed that American Airlines basically blacks out award space for several weeks from mid-December to mid-January on all or most of its routes.
What I Mean by Blackout
This isn't a hard blackout during which you can't use miles at all. It's a MileSAAver blackout. No MileSAAver award space will appear on a route for about a month, so you need to spend 2-4x the MileSAAver price if you want to book an AAnytime award.

For a quick refresher, MileSAAver is American's cheapest level of award space and its most heavily capacity controlled.

American Airlines, United, and Delta fly flat beds on their daily flights between New York-JFK and San Francisco and Los Angeles. Delta also flies its flat beds between New York-JFK and Seattle.

All three airlines compete in San Francisco and Los Angeles. Only Delta flies between Seattle and JFK with flat beds.

Which has the best flat bed award space on the routes?
What are the prices? 
What are the products?

The Products & Prices
Delta

Delta throws 757s and 767s configured with flat bed seats at its transcontinental routes.

American Airlines has released a ton of Business and First Class award space on its 777-300ER from Los Angeles to London this summer, fall, and winter.

This is fantastic and surprising news because American Airlines 777-300ER has world-class Business and First Class flat beds, American hadn't been releasing any space at all on its flagship plane, and American Airlines offers the cheapest Business and First Class awards to Europe.

Business Class Bed

Maybe with the 787 being loaded onto American Airlines' schedule, American Airlines feels less need to protect the 777-300ER's premium cabins.

American Airlines is the king of off peak awards. It offers economy off peak awards to most regions of the world. To some regions, you can get the off peak price by flying any of American Airlines' partners.

I don't think there's a single MileSAAver award seat available in Business Class on the brand new American Airlines Dreamliner.

American Airlines has taken delivery of its 787 Dreamliners.

I'm sitting on around 100,000 US Airways miles, and I can always get more by transferring in SPG Starpoints at a rate of 20,000 Starpoints to 25,000 US Airways miles.

If I do nothing more, my US Airways miles will be transferred 1:1 to my American Airlines account some time between April and June. I already took a minute to link my accounts to ensure a smooth transfer.

I gathered several estimates for the timing and extent of the next American Airlines devaluation from miles and points experts. I've averaged the guesses to produce a wisdom-of-the-crowd estimate that I hope is as close as possible to predicting the future as we can get.
Background
Last year, United gutted and bifurcated its award chart for Business and First Class redemptions. Now awards on partner airlines cost a lot more than they used to. For instance, one way in Partner First Class to the Middle East is 140,000 miles.

Delta released a few new award charts last year.

Through March 15, 2015, most transfers of hotel points to American Airlines miles earn a 25% bonus.

American has charged $25 per domestic ticket and $35 per international ticket to book award tickets by phone. That meant a lot of paying $35 for me, since only 9 of the 24 airlines you can book with American Airlines miles are bookable on aa.com.