I think it depends on how soon you are planning to go cross country. If you might head out next summer, it might be wise to upgrade now, before your tour from Seattle to Sacramento. If you aren't expecting to do a cross country type tour for several years, you might be better off waiting for a few seasons before investing in a major touring bike.
I think you could probably get away with doing a cross country on your Giant with only a few modifications, if you were so inclined. I prefer drop handlebars, but you can really tour just fine on that bike.