Darnley is nice but if you drive up there for the sunset, just remember that you'll be driving back after dark on winding pothole filled roads. All of PEI is a beach, so you may want to stick closer to YYG. Brackley Beach, which is part of the national park, is 15 minutes from town. I'm not sure when they start charging admission to the park but it may still be free in May.

Also, May is still a bit early for any tourism operators to be open, so keep that in mind if you are looking for meals or activities outside of Charlottetown. Most just open for July and August, some extend from June-October.

I've never tried the oysters, but the Merchantman Fresh Seafood & Oyster Bar is a very good restaurant in downtown Charlottetown https://merchantman.ca/