We have tried both - radios and cell phones. What we have found that works the best is to use the text message feature of our service. Initially we did this because our cell plan is statewide, not nationwide. We found out that t/m's were only 10 cents per message no matter where we were sending to or from.
In addition, there are several other advantages.
1.) A message will go through even with only one or two bars of signal. Great for those "iffy" areas.
2.) I set the phone for vibrate and ascending tone for a message. This way if I'm in an attraction I will usually feel the phone before I hear it. I can then choose to either read the message then, or wait till later.
3.) Reading or writing a t/m is far less intrusive to the others around you that talking on a cell phone. I really like this !
4.) No misunderstandings. What you sent is what they read.
You can also use most phones to send short emails. Once I showed her how, my wife got a big kick out of being able to send and receive emails from her sister at work, while lounging poolside at Stormalong Bay. A tough job, but somebody's gottta do it .....
Try this next time you're down at the World. You may be surprised how useful you find it.