Anchorage Museum is a great option for those rainy days in Girdwood.
This is also a nice non-rainy day trip too! It is huge and well curated, with tons of expeditions and 1000’s of art pieces. Kids and adults will love the 100s of hands-on exhibits and Spark!Lab. Lots of fine art and my highlight was the massive native culture installations.

Discovery Center
Check out the Discovery Center where you get to explore earth, life and physical science in numerous hands-on exhibits. The kids will especially enjoy the Spark!Lab Simithsonian exhibit that encourages creative problem-solving.
Cruisin’ The Fossil Coastline
View Alaska through the eyes of this “walrus-and ammonite obsessed scientist and artist with a fondness for cheeseburgers, ratfish, and trilobites.” This is another family-friendly exhibit with life-size sculptures.

Photo Credit: Anchorage Museum