West End is where the "main strip" of Roatan is. It's "Main Street" of tourist-town. This is where the highest concentration of restaurants and dive shops is. It's also where the drinking goes on, and there's not really a good "beach" in West End (There's one on each end, but I don't love either). West Bay has the beaches and is kind of a long row of resorts. They're not super high end but they're definitely "nicer" than the West End spots. Most spots on West End are "dive bar" style.
The walk from Luna Beach to the nearest side of West End is about 15min on the beach. There are water taxis that take you from West Bay to West End, as well as regular taxis. Sueno Del Mar is on the far end of West End, nearest West Bay. On the opposite side of West End from Sueno Del Mar is Seagrape Plantation. I haven't been to Seagrape, but Luna Beach is much, much nicer than Sueno Del Mar which is basic but fine. It's also a little closer to some of the party spots you're trying to avoid than Seagrape or Luna Beach, but should be fairly isolated from a lot of that.