Mat-Su Valley
Matanuska Glacier - The Matanuska Glacier is over 20 miles long, and 4 miles wide at the base. It's one of the few glaciers accessible by road (entrance fee,) and is well suited for a trek out onto the glacier with kids. At Mile 102 on the Glenn Highway (Route 1), look for the blue sign on the Glacier Highway that says "Glacier Park and Glacier Access."
From the parking lot, there's a trail to the face of the glacier. If you go further onto the ice without a guide, don't let the kids wander or run on the glacier.
We took a guided three hour trek onto the glacier and it was well worth it.We were provided with crampons which made it easy to walk up and down on the ice. Our guide pointed out different features of the glacier (it's a giant waterworkds), and we went right up to the blue ice pinnacles (it felt a little like being on Mount Everest). Filling water bottles with pristine glacier water was an experience too.
Tip: It's ten degrees colder on the ice, more if the wind comes up. Even on a sunny day, bring jackets and gloves for everyone in the family. Guided treks on the glacier are for kids 6 and up, and they have crampons and boots in kids sizes.
From the Glenn Highway, there's also a turnoff for the Matanuska Glacier State Recreation Area. You can't get to the glacier from here, but there are lovely views and picnic tables - it's a great spot for lunch.
Rafting on the Matanuska River - The melt from the Matanuska Glacier feeds into the Matanuska River.  Go for a raft trip where you'll put in just below the lake that forms at the terminus of the glacier. Easy raft trips, no experience necessary, last about two and a half hours.  For kids 5 and up; the raft company will supply life jackets and all the gear you need.
Independence Mine State Historical Park (Hatcher Pass) - Robert Hatcher discovered gold in 1896, and the Independence mine was a big gold producer, operating until 1951.
Visit the mine to get a taste of life in gold mining camp in the early 20th century - the bunkhouse, cookhouse, assay office, mine office and commissary. Follow the Hard Rock Trail up to see the water tunnel into the mine and electric train cars that transported ore. Continue on the Mill Loop Trail as it winds over the alpine tundra. Picnic tables and restrooms, and bring your own gold pan to try panning for gold in the stream near the mine buildings.
From Palmer, take the Hatcher Pass Rd., then turn off on Gold Cord Rd. to reach the mine.
Reindeer Farm (Palmer) - Little kids will enjoy a trip to the Reindeer Farm (off the old Glenn Highway). On the short tour at the farm, kids can see baby and adult reindeers, pet and feed them. Also at the farm, deer, elk, two moose and a shaggy bison.