Cape Henlopen has an excellent beach with trails and camping near. They have ramps for the pier and ramp to go down onto the beach. It's a good experience for a quieter day of sun and ocean waves. I find these State Park beaches are popular in high season, but they settle down nicely after 2 pm in summer. Then, all day they're easy-going after the beginning of September.
I saw designated areas for dogs, and I promised our teen son we'll have a day with his little dogs. My husband and I spent a day there October 1st and it was busy but not crowded. The views of the lighthouse, the ocean, and sand dunes behind us made the day. This State Park and beach rates high in my book for having an accessible beach for disabled, plenty of parking, dog friendly sections, and being quieter without boardwalk noise, or street traffic.