Used to be that if you took the middle tier (seat+bag+meal) you'd be able to select any economy seat for free, including first and exit rows. I checked a bunch of long- and short-haul flights yesterday and they are now charging extra for first row, exit row, and front of the plane. Price varied by seat and route - around $8.50 for a short-haul front seat, to around $70 for long-haul exit row.
Not sure when this change happened, but a few weeks ago those seats were still definitely free.
Note that TAs can still select any available seat, but their fare basis is higher (although it comes with 2 bags, not one). Also, you can't use the NOK trick to save a bunch of $$$'with them