Larry Fitzgerald is the most well prepared player in this draft...mentally and physically. Robert Gallery is a close second.
The other WRs are very talented, but they don't match Fitzgerald's combination of mental and physical toughness. The only one, IMO, who comes close is Michael Clayton of LSU. Mike Williams of USC is a special talent, but he's not going to exploit the middle of defenses very well for a couple of years until he matures. Roy Williams has all the physical gifts...but his head is not always in the game.
As for trading down for Wilfork...that, IMO, would be an egregious mistake. Miami had a real hard time stopping the run the last two years...and Wilfork was not the answer. He's just not a very productive player. He will dazzle you from time to time with his physical prowess, but he takes a lot of plays off and he shows little stamina. Plus, he's not a consistent pass rushing threat...which is disappointing for a player his size.
If the Cardinals were to trade down to #7 and they were thinking defensive line...the standout there is DE Kenechi Udeze of USC. This guy is the real deal. He's a flat-out warrior on the edge and a relentless pass rusher. He lacks ideal height, but actually uses his smaller size to his advantage to slip under, through and around the larger tackles.
DT Tommy Harris is an enigma. He showed up huge against lesser competition and was a non-factor in this year's biggest games...the Big 12 Championship and the Sugar Bowl. Harris is on the small side...but he's got excellent feet and good strength. Seems like a risk as a top ten pick.
This year's DT class is weak. The physical dynamos of the group...Wilfork, Tubbs, Washington, etc....were not consistent players at the college level which makes one wonder if they could possibly be at the pro level. The slighter, more lean DTs like Harris, Starks and Dockett were more productive in college but are they too small or slight to make a consistent impact in the NFL? I think they are all over-rated.