I like to travel with a group of people for several reasons- being able to share the experience, makes for fun conversation, I don't have to drive and for safety in numbers. So when I book personal trips, I like to see what group tours travel companies are offering and pick one. The nice thing is that most of the details are figured out for me- I just have to get myself out to wherever the tours start. It's a lot less stress on me which means I enjoy the trip more.
Enjoy your visit to the Grand Canyon- I went there for the first time this summer and it was gorgeous! If you can, try to get out there for either a sunrise or a sunset (or both, as I did)- it's breathtaking with all the colors and shadows in the sky and the canyon.