Oregon, Delaware etc no sales tax.
Coach in US is cheaper than HK's. Coach outlet in US is every cheaper. Sometimes they have very good deal... take extra 40-60% off the already redline sales price.
Not sure about Canada's price. But my impression is all those stuffs selling in Canada are more expensive than US's price.
I don't think there's LV's outlet. Seatle's outlet has Coach. Also, if your coworker has meeting in San Jose, they can check out the outlet in Gilroy too (about 30-45 minutes drive) if they have transportation to get there. Gilroy has Coach outlet. Sales tax is around 8.25%.
美国的牌子在美国买是比香港便宜的... depends which brand. But yes for Coach, Abercrobie & Fitch etc (HK has the 水货 or fake stuffs.)