I'd think the "WEZW" format would do well, as both Philly and Wilmington have significant Boomer populations that would like to hear that music again. You don't only need to approach nursing homes and funeral parlors for spots either. Boomers are still buying all sorts of things including cars, smaller homes - as they downsize for their eventual retirement, clothes, shoes, CD's of music, computers, MP3 players, I-phones, DVD players and DVD's, time sharing places for vacations, RV's for travel, pizza, eating out at restaurants in our local area -many of us seem to enjoy eating out, food as many of us also like cooking and shop at local supermarkets, kitchen gadgets for those cooks, home heating oil/gas, and related products, and on and on.
Most boomers have discretionary money to spend. Radio and their advertisers don't seem to want to target our dollars for their businesses. I find it hard to believe in a market the size of Philly #8 and even Wilmington's much smaller market #76 couldn't make one profitable station doing that format.
Everyone is going for the low hanging fruit of the youth and ignoring the fruit higher up in the tree, the boomers, that is virtually untapped in the Philly/Wilmington markets.