They are both in opposite directions and time may be a deciding element. Thanks, RGreenway for your comments as that is the kind of recommendation I was hoping for.
RGreenway wrote:
I agree that both are well worth seeing and photographing, but if you can only see one, I would vote for Valley of Fire! Much more "fire" than red rocks, nice short hikes to good photographic subjects. Red Rock Canyon is also good and a shorter drive from Vegas, but Valley of Fire would be my choice! Late afternoon is wonderful!