People often ask us about what are the best walkie talkies for wedding photographers and wedding videographers and the answer is pretty easy: Motorola Professional CLS1410 5-Mile 4-Channel UHF Two-Way Radio (click this link or the embedded link below to purchase). Here is a link to purchase a 3 pack of walkies.
Pros: Long range (up to a half mile and will work if you and your assistant are on separate floors of a hotel). A ton of channels.
Cons: Not bluetooth compatible. They are a popular brand so in some locations you will need to switch channels as to avoid other people who may be using them. The walkie talkie does not come with a headset (click this link or the embedded purchase link below to find the headsets on Amazon).