KSEA-FM (owned by Bonneville at the time) 100.7Mhz, was located at the KIRO-TV QA site. And of course, KING-FM 98.1Mhz was at the KING-TV QA site.
There was a lot of concern when the Colombia Tower ('box that the Space Needle came in.'.) was built, that it could carve a QA-no-signal-swath from Queen Anne Hill toward key areas Southeast of downtown. In the end, that never happened, although one could argue there was likely increased multipath to vehicles passing, or homes in the shadow of the Colombia Tower.
The only reason those stations abandoned QA hill, was that the majority of stations were consolidating to Cougar and WTM. They rightfully felt coverage parody with competition would be important. Ironically, there were a lot of nay-sayer's about KUOW-FM choosing to remain on the KCTS-TV tower on Capital Hill, rather than signing an expensive long term lease on Cougar, or WTM, not to mention the significant capital expense of moving. I guess KUOW got the last laugh on that, because history has shown their programming out-performs any perceived flaws in coverage verses the mountaintop sites.
Ultimately, content is still King.