Despite your saying you don’t want to rent a car, I would strongly recommend it if your preference is to get off the beaten path as you’ll be able to get to far more places without taking ages or spending a fortune. I don’t believe Uber operates there. Cabs are of course an option, as is Cabify, but it will be pricey if you want to explore much.
Penedes is a wine region, so I’d suggest a winery or two. You’ll be along the Costa Dorada, with great beaches. Cala Fonda near Tamarit is one I’d suggest. You might want to explore Tarragona’s Roman ruins, go for a vermut experience or to the Gaudí museum in Reus.
I’m assuming you’ve been to Barcelona?