I think anymore it is hard to predict future rates. If you're comfortable spending $400 PP RT, book it now.
I just booked tickets for my Feb 11-18 trip. $432.80 each after taxes/fees. There were limited flights with the times I wanted since it's about 8hrs on the plane each way for me coming from WA state and there are no nonstop flights. I watched the fares for a few weeks, and when they went up and up...and finally came back down again, I jumped on it. One of the legs of the return flight is already pretty booked so I'm glad I booked when I did, and now I don't have that part to worry about. I would be kicking myself if fares kept going up and I didn't book earlier. Then again, if fares go way down I will be partially upset...but it's better than not being able to pick a decent seat.