We’ve stayed at both. Usually we stay at the Phoenician (main property, Canyon Suites or Phoenician Residences). One year we decided to try out the Westin Kierland — after all the relative points discount was attractive. After 1 night into our 5 night stay we checked out. Despite a nice suite upgrade to a casita, the place was over run with people. We were struggling to even find two chairs together at the pool. It definitely had more of a party/loud/family resort vibe, not a sweet, peaceful baby moon!
We wrote to our contact at the Phoenician that we were coming back, seeking sanctuary from the madness! When we arrived, we were whisked to a casita 1 bedroom upgrade. Beautiful. Ended up extending our stay two more days.
The Phoenician is easily our favorite US resort with our family. (Or without!)