Here's some of what I think are the best parks in northern Utah County. I'm sure there's plenty more, we just haven't made it to them yet. This list is in no particular order.
Address: 452 W 400 N Saratoga Springs, UT 84045
Why it's Great: huge climbing pyramid, play structure, nice separate play area of younger children
Caveats: it's a newer park, so not a lot of shade
Address: 1450 North 800 West, Orem, UT
Why it's Great: Big play structure, swings.
Caveats: Some of the older kids like to climb up the outside of the big slide. If you have an adventurous little one, you might want to keep an eye on them. This park isn't amazing, but in my mind this is how an average park should be, but often aren't.
Address: 1435-1511 N 100 E, Pleasant Grove, UT 84062
Why it's Great: Huge amazing wooden play structures. This is a great place to let older children run free.
Caveats: Not really for younger children. The slides are really high off the ground. There is a younger child's area, but my little kids quickly bored of it and wanted to go with the big kids, so I had to follow them everywhere.
Dry Creek Trail Park
Address: 100 W 1580 N Lehi, UT 84043
Why it's Great: Nice play structure, creek to wade in, short walking trail with bridge that crosses the creek, Frisbee golf course, big old trees to climb, nice restrooms (for a park)
Caveats: lawn is not in good condition, lots of weeds, but a great place for kids. I'm not sure if the creek is running all the time or just when the irrigation water runs
Nielsen's Grove Park
Address: 1931 S Sandhill, Orem, UT
Why it's Great: Cool swings that move in a giant circle (think swings like at the fair), small play structure, trails for walking, fountain, pond with ducks
Caveats: circle swings aren't always working well
Other Cool Parks:
Draper City Park
Address: 12500 S 1300 E, Draper
Why it's great: manual exercise equipment, play structure, electronic play toys
Address: 600 E 900 S Salt Lake City, UT 84104
Why it's great: huge splash pad, two big play structures, lots of walking trails, big pond
Caveats: I haven't actually been there in the summer yet, very pretty in the fall though.
Children's Discovery Garden
Address: 3900 N. Garden Drive, Lehi, Utah 84043
Why it's Great: splash pad in summer, hedge mazes, small stream to race boats, caves, spider web for climbing
Caveats: This is part of Thanksgiving Point and costs money ($6). Closed during the princess festival.