Hi Danny! A group trip to Disney World sounds great to me!
Since it is your first visit, I think hitting the Magic Kingdom first would be a good idea. It was the first park in Florida, and will give you that first "Disney magic" feeling that you will be looking for. With Cinderella's Castle and Main Street USA, it will definitely set the right tone for your trip.
As for how many days at each park, I think that will depend a lot on whether or not you are traveling with small children. When my boys were small, we would spend the morning at a park, go back to the resort to rest, and then go back to a park in the afternoon. We usually planned to visit each park at least twice, and sometimes would re-visit our favorites more than that. Our favorite park is Epcot, so we usually go there three or more times on a long visit.
Any day would be fine for any park. If you really want to research it, you can visit www.touringplans.com. They give you a very good park crowd level estimate for the next year, and they even tell you which park is best to visit on each day. I have often heard that Magic Kingdom is the most crowded on Monday. All of the parks absorb crowds really well though, so you don't need to worry!
Also, have your entire party look at all of the great information on the
Walt Disney World website. You can read about attractions at all of the parks and get a head start on planning what will be a "must-do" for you!
I hope this helps! Please let me know if I can help you with any other questions as you prepare for your first Disney World vacation!