Definitely put in a 50a 125/250v circuit on a 14-50R, it's the de facto standard for bars and small clubs pretty much everywhere in the country. If you want to get crazy and be really prepared put one on each side of the stage, on separate circuits. A California connector would be fine too, although anyone that uses California connectors has a range plug adapter to plug in with, but not typically vice-versa. In my opinion you'll be in good shape if you install a 14-50R (or two).
If the 200a service is solely for this stage, and it's a 3 phase service, put in a 100a and a 200a fused disconnect, in case you get someone with a real distro at the venue.
Also, be sure to put in at least a few (4-6) dedicated standard 20a circuits at strategic points around the stage, for small systems, people without distros, and general purpose stuff like worklights, stand lights, fans, christmas lights, confetti cannons, or whatever crap someone wants to plug in.
I would hate to show up at a venue and only have 3 L14-30's to plug into. In fact, I've never seen a L14-30 installed in a venue, although I was at a tiny place once that had a 14-30R range plug installed. But that was just that one place, one time, otherwise all the small places I know of that have more than just edisons have 14-50R range plugs.
Just out of curiosity, how do you normally plug in your racks? Do you have a larger distro that you typically use? L14-30's are really uncommon in this industry, in my experience.