Good idea. But I think it's a bit strange to have -8 (Pacific) for the US. -5 (Eastern) feels like the "default" time zone, and IIRC slightly under half the population lives in it. -6 (Central) is probably a good compromise - I've gotten used to it working for a company that has people in Eastern, Central, and Pacific with a Central-time headquarters.
(It seems even stranger paired with -5 for Canada. Surely these should be the same?)