ive always picked Rbs early, Wrs middle and Qbs late, and thats traditionally the best route from my experience. im thinking of changing my strategy this year though, because in a few mock drafts ive been able to get top WRs early and still get about 4 quality Rbs with upside much later in the draft-Pierre thomas, Wells, Knowshon, Bush, and even late guys like Ward and Benson have some potential. The WR pool dries up by about rounds 4-5 and if you dont have them set, you're forced to take guys like Berrian and Breaston as your #3WR. As for Qbs i think waiting till middle rounds for guys like Rodgers, romo, rivers, Warner is better than jumping early on peyton,Brady, and Brees. Even late guys like Quinn, Edwards, hasselback could have some potential to be this year's Rodgers. The dropoff is not much (if any) and it frees up your early pick to take Rb or WR instead.
I think you definitely want 1 WR in your top 2 rounds this year, and you can wait on the Qb until the middle.