JW Marriot Desert Ridge or Westin Kirkland
 

Which has the best pools? Other comparisions?

Don't know, haven't stayed at either. I would go to www.tripadvisor and see if there are any reviews on the two resorts. I think you mean Westin Kierland instead of Kirkland. The Kierland Commons outdoor mall is a great way to kill an evening after dinner.

WHich of these two would be more fun for kids?

We've stayed at the Kierland, so I can comment on that. They have a "river" type pool that has a current so it flows around a fake island. There are inner tubes you can float in and go round and round, it's pretty fun! Another adjacent pool has a very shallow toddler section, then there's a separate adult pool next to the spa. Other than that, I don't recall much else for kids. The Commons is walking distance, very nice shops.

I've stayed at the JW Marriott Desert Ridge - it has a lazy river, too. The two resorts are in the same relative location in Scottsdale, so competitive on all dimensions. I've heard the rooms are small at the Westin - the rooms at the JW Marriott Desert Ridge were roomy (although not spacious). The Marriott is near to the Desert Ridge outdoor shopping complex with movie theatres and restaurants - lively night life. It reminded me of how Disney would do shopping and entertainment in the desert. Both places are nice, so you won't really go wrong.