If anyone is going to Pompeii, we hired a great tour guide... Gaetano's Pompeii Tours!
The advantage of having a tour guide is that Pompeii is a large place and takes a while to walk it. This tour that we took was customized to what we wanted to see, which greatly reduced the time that it would take had we done it on our own.
The other advantage of the tour, is that they picked us up from the airport before the tour, and dropped us off at our hotel after the tour which took a lot of stress on how to get to Pompeii with all of our luggage, and we did not have to worry about how to store our luggage when at the city.
We had a 4 year old with us and our tour guide was fantastic with her. It really made a difference. We were able to see many things as well as have things explained to us, it was really worth it.
My suggestion, if you are going to Pompeii, hire a tour guide to take you through it, but not any tour guide, hire Gaetano, he has been doing this for a long time and his discussion about the city comes from a realistic positive point of view.
For more information, you can checkout his website www.pompeiitourguide.com.