I only have experience with riding the West Coast. I have visited Midwestern and East Coast cities before, but I've never ridden in them. I'll add in another vote for Portland, Oregon. Also Davis, California if you prefer a smaller city with a "college town" feel.

In Orange County, I like Irvine and the coastal areas (Huntington Beach, Newport Beach, etc.). The cost of living in these areas is also quite pricey, compared to the non-bike friendly parts of OC.