Convention planners think of Vegas as a place that has cheap flights in and out, and offers an "adult perk" to their attendees. Logistics are pretty good and about the only downside is that some folks attach a "all pay, no work" stigma to events held there. It's easy to blow off a session and gamble in the casino. Folks often spend all night partying and try to recover from little sleep while attending events during the day. Orlando is thought of as a more family friendly kind of place, and even one that is less distracting to the adult attendees of an event. Costs and logistics are quite as good as Las Vegas but it can still be a very attractive venue especially if a organizer is trying to avoid the stigma I mentioned above. Once you get everyone to your event site in Orlando, it can be pretty great especially of you keep it self contained on one property. Most large groups will alternate between Vegas and Orlando unless they sign a multi-year contract. Both cities lack the kind of union hassles that you find in NYC, Chicago, SF, and some other places. I've only used cabs in both cities, and of course the monorail and walking are options in Vegas. When I managed events in Orlando we hired buses for attendee transportation.