First thing I look at in a pro shop is how much training and experience do they have AND what they do to continue that training. That includes industry knowledge, training seminars, and other certifications needed to keep ahead of the learning curve.
The 2 best pro shops in the DC/NOVA are are Sports Plus Carmen Don in Alexandria, VA and Red Nelson's Bowlers World in Clinton, MD. I believe both have been in the business before well over 20 years.
SPCD have extremely knowledagely drillers like Jim Lewis and Mike Sinek. Both are long time competitive bowlers outside of league conditions (Jim is a multi PBA regional champion and Sinek is former U of MD coach and Team USA National finalist).
RNBW is an IBPSIA certified shop with Gary "Guru" Parsons being one of the key board members of IBPSIA. Gary knows EVERYONE in the industry and is extremly knowledgable.
There's more to being a ball driller than punching holes. The above drillers have the knowledge and experience to do more than just use the drill sheet included with the ball.