For sure go to Coloma...it's a cute little town and shows where gold was first discovered, a blacksmith and you can even pan for gold. Bring a picnic lunch and some outdoor games because there is a nice big lawn area and picnic tables.
Sly Park rec area in Pollock Pines has a small lake, which would be fun to play around in and bring a picnic lunch.
There are a ton of wineries in El Dorado and Amador counties. Boeger is in Apple Hill/Camino and easy to reach from the highway. Wine tasting isn't exactly conducive to 17 and 13 year olds, but Boeger has a nice area for a picnic or just bring some cheese and crackers and then eat a meal at the Apple Cafe on the way out.
Tahoe is a little bit of a schlep, but totally doable for a day trip - if your 10 month old could handle it. You could take the tram at Heavenly (and the views really are heavenly), go see the lake and there are a ton of places to eat.
Take in a River Cats game - those are very family-friendly and so fun!
There are a ton of museums downtown and I'm pretty sure there is one inside the Capitol. Or the railroad museum or Sutter's Fort.
If you want a nice dinner go to Michelangelo's on I Street in Sacramento. You'll want to go back every week!
Old Town Sac is pretty fun too. We always make sure to stop at the salt water taffy place and go crazy.
Enjoy your visit!