If your hotel has bikes available, there is a bike trail to Playa Linda and through a nature preserve that we did several years ago. If they don't have bikes your hotel may offer tours or you can rent bikes in Ixtapa. For more info search this forums older posts.
A bus from Ixtapa to Playa Linda see the crocodiles, giant iguanas, turtles in the enclosure by the bus stop. Past the crocodiles is the ferry to Ixtapa Island where you can lunch and swim in bays on either side of the island (short walk between the two).
The path through the nature preserve is on the other side of the street from the Playa Linda bus stop. We go there every year and walk part way in to see the nesting birds (egrets, ibises, herons)
Take the bus to Zihuatanejo (10 pesos I think). See the main market, walk to the pier to see the fishing boats, see the restaurant reviews and pick the type of restaurant you enjoy. If you stay after dark, taxis are everywhere and not expensive.
Similar questions have been asked before so searching/scanning past posts with keywords with type of activities you enjoy will give you more specific details.