After last year's dramatic increase in airfares, meeting executives may be looking at the new year with less than great expectations. Yet many airline analysts expect fares to stabilize or decrease in 1997. "I think airfares overall reached a peak around Labor Day of 1996," says Terry Trippler, editor of the Minneapolis-based Airfare Report. "In 1997, barring any fuel-cost catastrophe, we will see fares not only level off, but moderate. There should be a reduction in overall fares."