"most value"... highly subjective based on your biz.
if you are an affiliate manager, i would say don't bother going to any shows. playing "spot the affiliate" game is useless....a wiredguy doesn't count
if you are a vendor (hosting, billing, traffic, marketing, etc), go to all of the shows.. always a few leads there you walk away with, and closing on atleast 1 usually pays for the trip.
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"most attendees"...not a measuring stick, but like with conversions, it is a numbers game.... if the door ticket was free, you could get alot of "riff raff" in. i know that the past xbiz vegas show got that criticism from others, but I thought it was a great move on xbiz's part to open up the show so that more could attend.
if there was riff raff, i ignore them. if it brought in more people that I normally wouldn't have been able to meet, then its worth it.
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"most decision makers".... that applies more to vendors.... as a vendor, if i can talk to the decision maker directly, then that helps alot with closing... so definitely an important factor.... but if you were an affiliate, that means nothing.
my overall characterizations of shows that i usually attend:
internext in vegas - its vegas, great time to enjoy vegas as well as do the convention thing. hate the palms hotel
xbiz in LA - great show, brings in alot of the LA-based folks (which is alot of the industry). didn't particularly like the roosevelt hotel, but definitely a great event. LA folks usually end up going home, so less of them to hang out with at night.
phoenix forum - great show, contained for industry, yet in social setting in the surroundings. they put alot of attention into making the event great for attendees
cybernet expo - smaller event, but alot of face time with companies. the tampa show was really small, but I got alot of biz done, and got to spend time hanging with people that i normally don't get to see at bigger shows. YNOT team puts alot of effort to make things work. I didn't make it to the SF shows, but have gone the prior 3 years.
xbiz at vegas - hot time of the year. not too keen about the hard rock hotel. brings in people to the show because it is in vegas.
internext in hollywood - contained environment, not much else to do unless you get a road trip down to miami. lots of places to hangout and chat with people. always a productive show as it brings in alot of europeans who find it a shorter flight to FL, then going for another 4+ hours to head out west. i noticed alot more european companies this year trying to make their break into US market
webmaster access west (LA) - smaller event, but brings in the LA crew and get to chat/hang with many people. since most live in LA, they end up disappearing back home, so less chance for that 1am - 3am time of hanging (some of the best biz conversations / bonding moments happen during that time) in the lobby and getting some additional biz done.
I haven't gone to any of the shows outside the US.... i am hoping to, but its an increased expense after already going to 3-5 shows already in the US.
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after 4 years of doing 3-5 adult shows and 1-2 mainstream shows, i have cut back. i didn't make it to Phoenix Forum, xbiz, and cybernet. I wasn't going to go to internext hollywood, but at last minute decided to go, and i am so glad that i did.
Fight the $0.04!