walkie talkies work fine here, the same way as anywhere else.
the "Reach/Distance" simply depends on the surroundings where You use them.
within a Mayor City you may find locations where they work only over the distance of a Block, while within a Flat Beach Area they may work over the distance of many Miles.
many Years ago we used them to stay in touch with small Boats working in the bavaro Area Inshore, mostly they been fine throughout the whole Area, from the Arena Gorda Area(Iberostar Hotels) til Cabeza de Toro on the South, been the Models with 5 Watts of sending Power, there are difference s in the Power of the different available Models. I am in no way up to Date what is available in case of sending and receiving powers of them Today's.
the Models You can purchase at the usual Stores here in the Country or in the USA do not interfere with the protected Frequencies used in the Country, no worries on that.
Mountains, High Rise Buildings, Areas of many Palm Trees etc are Killers for the signal and Cut down on the Distance of functionality a lot.
in case You Plan to Live down herev a Family Plan with a Flat rate for the Calls between Family Members on the Cell Phones would be what I would recommend for a Family, if You ask just to stay in touch with Your Teenagers while on vacation over very short Distances like within a Resort or such, then Your Walkie Talkies will do the Job, too.
Mike