If I could/would only do one which would it be? That's a bit of a tough question to answer. Both shows are great with SCI being a bit larger than DSC. But SCI also costs you a bit more with the required membership and more expensive ticket cost. You can attend all 4 days at DSC for like $50 I think it is. SCI it's a couple hundred.
Las Vegas of course has it's attraction if you want to do gambling and/or shows. Gambling isn't my thing, the shows are good, but also pricy. Food and drink in Vegas is also expensive anywhere on the strip. Hotels with fairly easy access to Manadalay can be had for reasonable cost. I do have to say that Vegas just overall wears me out. Outside of the hotel room, it's always noisy, it's always dark inside the casino's, the neon lights, yada yada yada. With being inside all day at the show, by the time the show closes for the day it's dark outside. I just find myself ready to leave in a couple of days. Hard to fully explain it.
Dallas hotels are on par if not somewhat more expensive than Vegas. But food/drink outside of the convention hall is more reasonable. Unless you stay right downtown Dallas you'll likely need a rental car, whereas in Vegas you won't if you're staying on the strip.
Just my opinion, but I feel like SCI is a bit more of a black tie affair whereas DSC is more boots and jeans. So I feel a bit more like I'm in my element at DSC than I do at SCI. But they're both great shows and it's as I say hard to choose between one over the other.
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now @PHOENIX PHIL when have you seen me in black tie at SCI???? boots and jeans.....
maybe i have actually been going to DSC and not SCI all these years and never realised....
never been to DSC but have been going to SCI since 1990 and have seen it grow and grow. you would have an eye opening experience whichever you choose to attend. i have had friends come to SCI with me and its very amusing watching their reactions ....the kid in the candy store ....well multiply that by 100 
