Oreets is quite right... as well, hiring a guide who can help you plan the best possible, but still flexible itinerary will only make your trip more enjoyable. It's great to explore on your own, of course, but you surely don't want to 1) keep driving over the same road again and again simply because you are not sure of the way or 2) miss some of the more interesting sites and areas simply because they are not on the map you are using or 3) have your group get to a site that requires a guide and be turned away (yes, it does happen)!
As well, a guide who connects to a local agent can help you arrange accommodation, transportation and all sorts of special activities to provide you with a full experience...
If you want to bring a large group, it would be advisable to work through a tour operator in order to include your airfare in the total tour price. This will also assure you of supervision while you are here in case any problems arise. And even a large group tour doesn't have to be "if it's Tuesday, it must be...." - with a licensed and experienced tour guide working through a licensed tour agency, you will have the possibility to adjust the itinerary even as you go along, making your tour one-of-a-kind!
Enjoy your visit to Israel!
suzanne
suzanne pomeranz
SuzTours: Every Day an Adventure!
jerusalem, israel
suztours@gmail.comhttp://suztours.blogspot.com