Have you started sweating just thinking about the logistics of getting all the members of your family on the plane, off the plane, and to your desired destination - let alone what you'll do when you finally get there? Don't fear! Yes, it will take work and planning, but enjoy the process and take the opportunity to learn about your destination. Be wary of over-planning; every minute of every day need not be accounted for or you'll be stressed trying to stick to an ambitious schedule. Find a few things you'd like to do and pencil them in, but go with the flow and allow yourself to simply 'be' somewhere.
This entire website is dedicated to helping plan a trip, but if you're looking for a step-by-step guide on how to start the process see How to Start Planning under the Obstacles tab. For other aspects that factor into your trip investigate the links below.