I spent the first 35 years of my life living in Southern California, and the late afternoon/evening launches from Vandenberg AFB were always a treat. The different winds at altitude always made the exhaust plume form crazy swirls and twists and the sun would give it different colors. Sometimes even when it was an hour or more after sunset the uper level exhaust plumes would light up like a sunset. Very cool.
I don't know how it would work on the east coast, maybe you need a sunrise launch? I guess we'll just have to wait and see.