Eh, I don't think this one is about coasts or city size. I think it's just luck of the draw in terms of which decades any particular city has its booms.
Atlanta &
Charlotte are full of ornately-crowned skyscrapers because their skylines boomed in the 90s amid the postmodern rage. But I guess they count as coastal, so about
Des Moines, a tiny city with one of the least boxy skylines around. Add in
Cincinnati and
Saint Louis and
Minneapolis and
Columbus and really plenty of others.
OTOH, until recently the gigantic coastal
San Francisco and
Los Angeles have both spent most of the last 40 years just as boxy as Denver, their one big landmark towers notwithstanding.