With 6 in your party, I would recommend a town car to get you to and from the ship, rather than the shuttle. Price should be about the same as a rental car and much less than the
DCL shuttle. I like the shuttle by the way but it can get expensive for a large group.
If you plan to spend time at WDW, I highly recommend staying on property as its more convenient to the parks, especially if you don't have your own transportation. WDW has hotels for every budget. Personally, I think a few days at WDW is a perfect combination with a
Disney cruise, but I know some may find that a bit too much.
However, if you're thinking of visiting Universal, Sea World, etc, a hotel near that location might be better.
On the return trip there are a number of hotels near the airport - just about any brand you want and most with shuttles to and from the airport. But I would recommend the Hyatt located in the airport itself. When you get ready to leave you just walk and check-in.
I recommend you purchase or borrow from your local library some tour guides for both Orlando and WDW. These will provide you with information on what there is to do (a lot!), as well as providing suggested itineraries, hotels, transportation, restaurants, and other activities (such as Downtown Disney).
My party of 4 will arrive the day before and spend the night at a nearby Marriott or Hilton (using points) and on our return we're spending 4 days at our DVC resort.
) and I've read some where that the Kennedy Space Center was really interesting, but it's lower on our list of choices. 
at the dinner table!
