Since there's a mention here about this not always appearing for all bookings, and the OP mentions the need for other tools, I wanted to point out another way to see this info.

If you try a booking on expedia.com, you'll get a seat map. I don't know how accurate it is, I just noticed it recently when looking to see how full an upcoming flight was.

Anyone with EF access want to compare and let us know if they show the same results?