I live in Phoenix. February is a fantastic time of year even for just a short weekend. Do not connect and it's easily doable. It's 4 hours in the air here and about 3 1/2 back so not horrible.
There are tons of nice places to stay. I'd look at:
Scottsdale-these are further out and in more residental/urban areas. They have more of the water park features beyond regular pools
Fairmont Scottsdale Princess
Mariott Desert Ridge
Westin Kierland
Phoenix-these are closer to central Phoenix and Old Town Scottsdale
The Biltmore
The Phoenician
Mountain Shadows Resort
Mariott Scottsdale Camelback Inn
The last two are basically at the base of Camelback Mountain. The last four are a short drive to many restaurants and shopping.
You can basically find a hiking trail within miles of all of these resorts. It just depends on what kind and how hard of a hike you want. I wouldn't recommend taking young kids up Camelback or Piestewa Peak. Those are pretty hard and usually pretty crowded. They're both about 2,000+ ft of elevation in about a mile. So basically straight up and scrambling over rocks at points. You can find a hike from super flat to straight uphill and anything in between very easily. Spring training will be here at the end of February if your kids like baseball. There are games all over the Valley pretty much every day of the week. It's fun even if you're not a baseball fan.
https://cactusleague.com/schedule.php