Yeah, early on I decided that cupholders (read: beer can holders) were absolutely essential on my cabinet.
Building them into the control panel is an interesting idea, I suppose, but to me it just seems there are much simpler solutions. I decided to simply hang one beer holder off each side of my cabinet so that the opening is about flush with the control panel surface, and just behind it. Simple install, inexpensive, perfect accessibility (well within arm's reach when sitting on a stool), one for each player, fairly non-intrusive from a visual design standpoint... for my needs it was a complete no-brainer, and I don't care if it makes authenticity snobs cringe.