Penedo has a rich collection of 17th- and 18th-century colonial buildings, including many churches. Unfortunately, regardless of the posted opening hours, these churches are not reliably open to visitors – your best bet is to walk around and see what's open.
Regular ferries (R$3.50) depart from the center for Neópolis, a hilltop colonial town with historic buildings and fine crafts for sale. During high season, it may be possible to get on an organized tour to the Foz do São Francisco (around R$70 per person), where the river meets the sea at a beach with dunes and natural pools. Try Farol da Foz Ecoturismo, located about a 30-minute drive south, for these and other trips in the area.
Options are limited, but the city is rarely totally overrun with tourists so you shouldn't have trouble getting a room most times of year. Make sure you book in Penedo, Alagoas and not Penedo, Rio de Janeiro state.
Several supermarkets, sandwich kiosks and self-service eateries are on the main waterfront plaza. There's a few good places to eat in town, but it's hardly a culinary capital.
Drinking & Nightlife
The most action you'll see is a few restaurants with tables and chairs out down by the water. Bring bug spray because proximity to the river means lots of insects at night.