I don't think the so-called "Spanish" audience in metro Seattle is large enough to support several stations - not that the ones already airing something in Spanish are anything to get excited about, since most are right-wing religious themed outlets from missionary broadcaster Salem. Salsa, anyone? Rock en espanol? Mariachi music, even?
There is a Mexican immigrant population here, but not nearly as large, vibrant or stable as in any city in California, from what I see. And the music on "La Grande" network is all "banda" from a particular rural part of Mexico, aimed at low wage workers and migrants. It doesn't seem to appeal to listeners from other backgrounds, whether born in Mexico, Guatemala, Puerto Rico, or Illinois. There are other kinds of Spanish-speaking people here, from Central America, South America, and second generations and later here, whom I assume mostly listen to other "mainstream" formats.
Are all three of the Punjabi stations aimed at Vancouver from this side of the border programmed by the same company? I recall local news reports a few years ago on CBC-TV from Vancouver about criminal charges aimed at people behind the time-brokered arrangement at AM 1550, (cross border protection makes Washington State analagous to Sonora or some other untamed part of Northern Mexico!). I don't know the full story, but it seemed like there were suspicions aimed toward some of the people associated with that station - and it seemed to precipitate bringing stations like Red FM (93.1) and others aimed at the area's big South Asian population to start up inside Canada.
All traffic on AM 730 is rather lame. Mostly ferry crossing reports. More updated traffic is on CKWX 1130 every ten minutes on the 1s. I lived in LA when KHJ experimented with that format for a few months, as a last ditch effort before being bought out and going, as you say, "Spanish." Maybe all traffic, with frequent news briefs, weather, sports, etc could work here. "Give us ten minutes, and we'll help you get out of the house."
Seattle sure could use sharper and frequent traffic updates on weekends and evenings, but with announcers who aren't just reading off of DOT maps, and who know how to help me as a listener negotiate around blockages, instead of just saying "find an alternate route," or resigning us to the all day backups that keep many of us out of Seattle for entertainment - it's not all just commuters, you know? (I mean, what's with those "reversable" lanes leaving the city when 5 times mroe traffic is trying to get in??)
I still haven't heard many suggestions that aren't replicating what's already been done or is airing elsewhere. There have to be more than only a half dozen viable program formats for commercial radio -- even on AM! You won't be in the "top ten" of the 6+ ratings, but that doesn't mean you can't serve a niche audience and at least break even financially. Maybe what they're doing now will eventually be such an example.