I have Treadwell as a top 15 player in this draft for the Steelers (basically eliminating 4-3 stars), so if he was there at 25 I say take him. Brown's contract is up in 2 years. If he's still the #1 WR in the league at that time, I'm not positive the Steelers can afford him along with our O-line, Big Ben, Bell (who I think the Steelers will extend this offseason) and any defenders we try and resign. I highly doubt the Steelers go WR in the 1st (or even the 2nd probably) but I would be surprised if they don't grab a WR in the first 4 rounds.
Also, I do like Coates and think he should be a quality WR for us this year, possibly taking the WR 2 spot, and Green should add a spark, but we have to assume Bryant won't be back and it's possible Brown leaves. So, 2 years from now our WRs could be Coates, Heyward-Bey, and draft picks...