Muir Woods is one of the most famous spots to see redwoods in the area. You'll have to reserve parking before you go so plan ahead. They have hikes ranging from 0.5 miles and wheelchair/stroller accessible all the way up to 11 miles with intense elevation gain so you can choose whatever is right for you.
Enjoy some brews at the Lagunitas brewery, headquartered right in Petaluma!
Napa Valley is, of course, known for its wineries! There are a few local ones in Petaluma: Reis River Ranch Winery, Parum Leo Winery & Vineyard, Azari Vineyards & Winery, and Keller Estate Winery. You might also branch out and explore some of the wineries in Sonoma and Napa.