If you are a traveler would you prepare for an itinerary or have an anything goes or adventurous schedule? Most travelers would prepare for a detailed itinerary to have a smooth trip. If your trip is business related, an itinerary is a must since days will be limited and it will be company sponsored. If you are travelling for personal trip, you have a choice to either have an itinerary or not.
Itinerary is a list of places and activities you will have from the time of departure up to arrival from your original destination including the flight details or any other transportation means you will take. Having an itinerary will maximize your time and have a more focused trip, but sometimes you will be stressed keeping up with it. While an adventurous schedule gives you more freedom and excitement but might end up missing the big part if you spend much time to a single place. Personally, I would take the first one so that I will always have direction for the trip, but will still be open for any changes that may occur.