Hello! My husband and I will be traveling to Spain in late August/ early September. I'm looking for recommendations for a portion of our trip. We will be flying from Mallorca to Bilbao, then renting a car from Bilbao and driving to the Rioja region. We will have 5 nights to stay in the Rioja region before continuing on to Madrid, and I'm curious if there's any recommendations with how to fill those days. We will be there from a Friday evening to a Wednesday morning. For reference we love drinking wine, eating yummy food, exploring new towns, and just getting lost in a new place. We also have not booked our lodging yet, so any recommendations on where we should stay/which towns are also welcome. Thank you!

Too little detail.
Exact dates would be handy to know because there could be a fiesta being held during your stay that could be great to see.
Accommodation would depend on what price range and facilitates you are looking for. Best look at something like Booking.com. They now have rentals as well as hotel type accommodations.

drinking wine, eating yummy food, exploring new towns, and just getting lost in a new place. will be found all over the region. Drinking and driving do not mix.
The lariojaturismo is a good website to explore what takes your eye. They have a route planner. Have you also thought about visiting a Monastery?