Besides the direct fallout from ash, I'd be concerned about ejecta from the actual explosion itself. Apparently there have been reports of finding yellowstone rocks as far east as Virginia.

That's a very sobering thought, but given the magnitude of such an eruption, not entirely out of the realm of possibility. The ejected mass of particles would also cool the earth for a short time before natural processes washed them out of the atmosphere.

I'd also imagine that the West coast would be isolated, since flying through that ash cloud is not something conventional jet airplanes are suited for. (Not any aircraft are really, due to the small size of the particles and their damaging effects to their engines.)

It would be a catastrophe, but ultimately survivable. Provided you weren't in the immediate blast radius and evacuated before the ash started to accumulate in large drifts.