I recall in the mid-90s tickets between ATL-DTW being in the $140-150 range. Also, about 12 years ago, tickets between ATL-ORD could be had for under $100 if you got lucky, and were still usually only around $130-150.

Back in '92, we also went to Seoul (ATL-LAX-GMP) over the summer. I recall that good prices for tickets around that time were around $600-700, with tickets usually more in the $800-1000 range.