Not sure if you are familiar with Ultra Signup, but they list many of the 50k races that occur in the country (not all of them, but a whole lot of them). Come to Utah in October and run on an island in the Great Salt Lake (not showing on USU yet but it's run by this outfit)!
If you are thinking Cali, check out Coastal Trail Runs. I've done the Spooner's Cove event. The 50k is two laps of the 25k--not my favorite. But Montana de Oro is amazingly beautiful. I have hiked the Skyline to the Sea trail; it's gorgeous. This would be an awesome run!
Coastal Trail Runs is an outfit that grew out of a division of the original Pacific Coast Trail Runs (which went belly up in 2011 but is back apparently). I did the Woodside 50k years ago. It was my first 50k. It was awesome. You run in the redwoods near Stanford and it is close to the ocean so you could make a trip of it.
As for books, I've read a few and probably like Relentless Forward Progress (Bryon Powell) the best. It's not the best writing in the world but it has a lot of good, practical advice. Also check out these websites:
irunfar
run 100s
Enjoy the training journey. No one ever does just one