Comments on location vs Westin if we are looking to do the touristy stuff with a kid? Universal, Aquarium, Kid Plaza. They might not have much interest in Kyoto or Kobe. Maybe Nara.
There is a Pokemon store in Osaka, if your kids are into that. You can supposedly buy things that are only available in Japan. I stayed one night at this hotel and it was fine, just a little tricky to find from the train station. It's actually next door, but they did not do what ever it takes (pay?) to have signage for the hotel placed int he station itself. There are good directions on the internet. When you find the ones that tell you to head toward's the second McDonalds (IIRC, it is near a Peek's Coffee), you have the right directions.