You have many more options if your visit is in the summer months.

In addition to Hopewell Cape (the flower pot rocks), you can continue along the Fundy coast in a westerly direction to Alma (for a good fish n chips meal as well), and the entrance to Fundy National Park. There are some interesting drives/hikes you can take in the park, or even play a round of golf. You can rejoin the TransCanada highway at the northern entrance to the park to get back to Moncton.

near Moncton
Buctouche: nature park on the dunes.
Sackville: boardwalk across the wetlands for birdwatching. Marshlands Inn for lunch, tea or dinner.
Shediac: Parlee Beach, warmest water north of the Carolinas.
PEI: if you are driving as far as the bridge, keep going into Charlottetown.
Saint John: 90mins from Moncton by highway. Lots of history.
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