Indeed, in terms of straight cume, WDVR was regularly one of the few FMs in the country to hit the top ten by the late 1960s... Add to that the fact that the audience itself was a very desirable one, it becomes even more evident just what an amazing accomplishment the station's efforts were... While the measurement methodology was somewhat different then, a 1970 report I saw years ago (ARB?) had WDVR in the number four position overall-- again, amazing... When thinking of FM in Philadelphia during the late '60s, everyone talks of WMMR as the outlet that put the band "on the map" here-- but the Kurtz and Lee team of WDVR was the one making all the real money!
All-news KYW was regularly in the top five by the late '60s-- during most of its time as NBC-owned WRCV (1956-65) it was a big-budget, 50,000-watt also-ran outside of a few programs... The other '60s-era station to regularly score well that hasn't been mentioned yet was WCAU, during its golden era of talk radio...