Who would be the first free agent you'd call on July 1st? The answer says a lot about how much you want a guy. If it was me, I'd pick Goran Dragic. I love Steve Nash, but unless Neil Olshey can assemble a contender in one offseason I'm not sure how much sense it makes to sign him. I'm not of the opinion that Deron Williams would rule out Portland, but I don't think he would be the best fit.
With LA as our All-Star, Dragic makes tons of sense. Three words: PICK-AND-ROLL. He's a veteran after four years, and has enough experience that he could be a mentor to someone like Lillard or Marshall if we drafted one of them. He's also likely to be around for several years, meaning he'd have time to gel with the rest of the team - a factor that's too often underestimated when it comes to building a title contender.
There's a nice article about Dragic at http://www.nba.com/rockets/news/steve_nash_dishes_on_goran_dra_2012_04_13.html that's well worth a read.