You just have to ask yourself: If United gives me the job to start in early spring, would I leave Delta? Contracts are comparable. I don't think the wife working at DL would be an issue. If DL was in trouble, chances are UA would be as well. Driving across NYC for your entire career would suck. Is international wide body flying a priority for you? Or a quick upgrade?

I think either would be a great decision, but I wouldn't pursue UA Unless you're pretty sure you'd leave DL for a UA class.