Hi Rebecca,
If money is not a factor, then between those choices, I would pick either the
Villas at Disney's Wilderness Lodge or the
Bay Lake Tower.
The Wilderness Lodge is a quick boat ride to the Magic Kingdom and is close to Fort Wilderness where your children can enjoy a lot of fun activities. The Lodge itself is stunning and is also home to the
Whispering Canyon Cafe, a popular and fun dining experience.
The Bake Lake Tower is a monorail ride away from the Magic Kingdom, the Park that 4 & 5 year old children generally enjoy the most. In addition, it is near
Chef Mickey's, a fantastic character dining restaurant.
While Old Key West is nice, it is further away from the Parks. I think you'll find being closer to the action to be a bonus. I personally would choose Wilderness Lodge out of any of the options above.
Hope this helps and have a magical vacation. Please let me know if I can assist you further,
Kaylene