[Walt.]

My best by far was Roy Orbison at the Bayside Amphitheater opening. Free concert and we got there early enough to get seats in second row center. 10,000 others showed up for an incredible show. He died about a year later.
High on my list would be Del Shannon (from about 8 feet away), Brenda Lee, The Searchers, ELO and Peter Noone (first seen in Ft. Lauderdale 20+ years ago).
Dozens more (Judy Collins, Gene Pitney... even Burl Ives), but these were standouts.