If it was in Las Vegas, then you saw Anthony Crivello (yay, Grantaire!) or Brent Barrett as the Phantom... Or you might have gotten an understudy. Brent only stuck around for about the first year or so of the production, though -- he left around mid-2007, and then Anthony took over full-time after that.
I've seen POTO in Vegas 5 times, plus once seeing the national tour in San Francisco and a couple of times seeing a local community theatre production. All of them were great, but I'd give Las Vegas the edge because although the show was trimmed down somewhat, the staging, cast, and all other aspects were just magnificent. Anthony was a superb Phantom every time, and you just can't beat a theatre built specially for the production and modeled after the Paris Opera House. I was devastated when it closed at the start of this month.
And so we don't get too far off-topic, The In-Between
sounds really intriguing! I probably won't get to see it unless they have a touring production that comes close to where I am, but hopefully there will at least be a cast recording for us all to enjoy.