[MNBlockHead]

I don't DM at conventions or the local game stores. The local game stores are not a great venue for RPG even if you don't have to worry about electronics. The noise of other games going on nearby and of shoppers, make it hard to build any atmosphere to your game. Conventions can be the same way. I've only played RPGs at conventions and while I enjoyed the games, it was distracting having people walking around you and other games going on in close proximity.

One exception is that at one of the smaller conventions in my area (Con of the North) if you can organize with a couple other game masters you can get your own conference room with 2-3 tables as long as you are offering a game during nearly all time slots. This is the ideal way to play RPGs at a convention. You generally have plenty of table space, easy access to electric outlets, any plenty of room for your stuff.

The trick, however, it that you still usually have more than one table that you have to keep running games at, so you don't want to run two RPGs in the same room, that's worse than playing in a main hall. With so many games going on in a large hall, they became background white noise. But when it is you and another game in a smaller room in close proximity, that can be very distracting. Better to have to other table(s) running board or card games.