Is there a reason these are so popular on the West coast and rarely if ever grown on the East? Will they tolerate high humidity? Are there any that are better suited for the Eastern US than others?

I don't think any of them are really suited for the eastern U.S. Most are hardy only to zone 9, and even the hardier ones would have to be planted deep and mulched heavily in winter on the East Coast. They don't tolerate high humidity, especially at night. They are tropical plants, but in the tropics they grow at the cooler and drier elevations. They like warm days and cool nights, which is why they grow well in the Pacific Northwest.