Where's a good place to find route maps for long-distance cycling? I'm trying to find the easiest route between Orange County CA & Las Vegas.
Have you tried your local tourist information place?
Machka & Rowan's Photo Gallery & Round-The-World Tour and other 2012 Photos
And link to ... Some of my favourite photo threads on Bikeforums
not LD-specific, but these sites have lots of routes on them:
Don't know if they have maps for the route you want, but adventurecycling.org has great bike specific maps.
...and a lot of states and counties put out bike maps - either recommended routes (which you could stitch together to get you where you're going), or an area map with roads color coded for cycling suitability.