Next booming market will be wherever Amazon's HQ2 is. I'm really hoping Pittsburg is chosen. Great town in need of a new industry to replace steel, coal, and other industrials.
Property values to current rents leave a lot of room for margin to be made on your down payment of a rental (unlike San Diego). That being said, most properties will need some serious rehab to be rented out at top value... but then you can refi and cash out to move to the next rental.