Hearst Tower in Manhattan remains the familiar textbook case study.
Base by Joseph Urban originally built in 1928:
(Photo from
Wurts Bros. collection of the Museum of the City of New York)
Tower by Foster + Partners finally added in 2006:
(Photo from
Hearst Corporation on CTBUH)
(Photo from
Simon King on Flickr via The Architect's Newspaper)
The howls on our city's review committees for even just a less daring, 14-floor version would never cease, but we see that it can be done successfully. The relevant wing of Joske's is not really that much different in scale, style, or type than Hearst's base, such that you can very easily photoshop Joske's into the image above. I fear, however, that only the most conservative, unassuming, and conventional add-on atop Joske's would make it through the process, and even Hard Rock, for all its brand imagery, will play it safe.