I think walkie talkies would be a little difficult. those things never work that great and if the resort is that big, i'm not sure they would be able to work anyway.
I would just setup a welcome reception. I'm just going to have everyone meet at the lobby bar at my resort so it's free since i've pretty much blown my budget. Make sure you get everyone's room numbers when they check in.
At fsil's wedding, everyone kinda just met at a certain bar everynight. it wasn't always planned but it worked out. And people didn't have to meet. Some people like to do their own thing on vacay.