[quote user="buddha"]OMG!! Claire, now i am nervous, more nervous than before lol! Glad i scrolled down and i guess that pic was last years What Hifi demo he he![/quote]
Don't be - it's a lot of fun.
From years of experience I'd say comfortable shoes, dump your coat in the cloakroom if it's cold outside, as it gets pretty warm up in the show corridors where all the demonstrations rooms are, and by all means bring some music or a movie you want to see a bit of - when it gets quieter later in the afternoon you may find some rooms willing to play requests, but most of them will be running demonstration material chosen to show the equipment off to best advantage.
Oh, and don't bother with the lifts at the Marriott, other than to get you up to the top floor of the show from where you can work down using the stairs. You can waste half of the show waiting for lifts, only to find they're full when they do arrive!
That's about it...