Hi Joe,
I recommend trying Villa del Arco, Villa la Estancia, and Villa del Palmar. They are wonderful condo-style resorts right next to one another. They are closer to town than Marbella, so you have the option to walk into town and avoid taxi fare. Villa del Arco is VERY kid friendly and even has a giant pirate ship near the pool for the kids to play on. I believe they have a kids program as well. The resort also does weddings.
As far as a coordinator, it all depends on how hands-on you are willing to be. Finding a photographer, officiant, etc will take some research, but you can really find everything you need on this site. Additionally, you'll get some help from the coordinator at the hotel/resort.
Good Luck and Congrats!