Hi Scooter,
In my opinion, doing an all-90s format would be next to impossible. In the first part of that decade (1990-1995), CHR radio was dying as the format became so niched that much of the former audience had left the format and was listening to other formats (Country, Oldies and AC for the older adults, Hip-Hop/Rap, Dance, and the various forms of Rock for teens and younger adults). The format during those years was in trouble when the M Street Journal had stated at the end of 1991 that 250 former CHR stations had left the format that year.
The former WANS was one of those casualties. (Yes, I know they went bankrupt and had to be sold off, but even before the end, WANS was leaning toward Hot AC). WBBO tried for several years, but never had any decent ratings or enough promotional dollars during their lifespan to make it work, despite undergoing several tweaks. There is one exception...just before the station was sold to Benchmark, WBBO started to lean toward Modern Rock, when the ratings had actually started to tread up, IIRC. Too bad Benchmark killed it, but that's another topic. It wasn't until then-owner Keymarket flipped WFBC-FM back to CHR several months later that the market had the format again. (I say back, since, prior to 1984, WFBC-FM was an Top 40 station, but one that leaned toward AC at that time.) This time, it was tried with a more diverse playlist, which helped paved the way for their massive success for the rest of the 90s.
Anyway, IMHO, it would be very difficult to do an All-90s Classic Hits-type format. The only attempt, thus far, was a few years ago in Sacramento, CA. While the music mix was on-target for a mainstream Top 40 station that played 90s Hits, the ratings never panned out and they wound up changing format within a year's time. The company formally known as Clear Channel had tried a "Gen-X" format (focusing from the late 80s to the early 2000s) in several markets, but that has also failed. AFAIK, there is one station in Green Bay, WI called KZRadio (WKZG, heard at
www.mykzradio.com) that is making an attempt to mix both 80s and 90s Pop Hits. That would be the type of format that I would love to try if I had to do a Gold-based format.
Robyn