A must see attraction if you are visiting Scottsdale with young kids in tow. Also a great place for locals to host a birthday party, picnic or let the kids run off some steam.
The main attraction is the train, free for kids three and under and one ticket (6 for $10) for everyone else. A $10 all day wrist band is also available. Just be prepared to scream at the top of your lungs when you go through the train tunnel. Secondary attractions are the carousel, a museum, a smaller steam train that operates limited hours, a great playground, and assorted jails... to climb on. There are also snack options available.
Operated by the City of Scottsdale, the RR Park is really just an elaborate city park. An amazing city park! It's not a full fledged amusement park. You'll be disappointed if that's what you're expecting. Your kids will need to run around and create some fun on their own, which I suspect they happily will do if left to their own devices.