Big venues are horrible places anyway.
I had a 'moment' once at a football match at St James Park in Newcastle. We were very high up on the stands, and as I stood up when the players came on to the pitch, I had a mild vertigo episode. It wasn't overwhelming though. I can see how it affects some people though..
I would buy tickets as early as possible to get seats on the flats in these places. The sound is always better down there too. That said, try and face your fear, you dont want to miss out. I wont call you a wimp; we're all scared of something. I have what is almost a phobia of MOTHS!!!! Hows that for a wimp? If someone had told me that a moth was flapping around Wembley Arena on the Rush R30 tour I would have refused to go in!

Ok, maybe not, but in confined spaces..