Tours give you the opportunity to see a lot, within a time frame. You get to see a place, its culture, treasures, and big sites, taste the cuisine, blend with the locals and then you're off again. Essentially, you get to sample the very best of a place and what it has to offer.
What are the advantage of tours?
Tours provide simplicity in planning by taking care of the details for you. They organize transportation and provide you with information about the places you're seeing. They are also a great way to meet new people and get your feet wet if you're new to travel.
Why Private tours are better?
Private tours allow you to choose exactly what you want to do and when. You don't have to depend on going with a group either, since there is room for flexibility and changes in your schedule. The freedom on how to spend your time is the main reason people choose private tours over group tours.