I had been watching the airfares for Thanksgiving since July. They went down a few weeks ago so I booked our trip to Orlando (Disney) then. I've also been watching the fares for Spring Break for the last 3 weeks. They have actually gone down and some flights are already SOLD OUT!

I still haven't booked it but I did find a lower fare yesterday if we are willing to change planes but the way it is looking now that is our only option since the few nonstops are sold out or only the higher priced fares left.
When I booked the Orlando trip I noticed that American had restructered their fares. When you are pricing it out make sure to check the "by price" box so you can see every flight and the price for each one. There are tabs across the top that tell you the lowest fare for the previous and following days. Makes planning and research MUCH EASIER!
I really don't think they are going to go down now. Southwest has had their fares thru March 6 out for awhile and just last week went ahead and priced out thru May.
All airlines notice if flights are selling or not and adjust accordingly. If the flights are selling fine w/ the current prices they won't change them to a lower price. By looking to see how many seats are available when your looking at the flights your interested in you will be able to tell if they are selling or not. Also by the price levels left that are available.
I look at the airlines websites, expedia, travelocity, hotels.com, bestfares.com, etc and so far the airlines prices thru their own websites have been just as low if not lower. Pricing out an entire vacation has been cheaper thru the airlines sites as well.