Ok, some of you will instantly think I'm moaning about never seeing L10s, 747s, etc., at CLE, but this is more then that, particularly with DL. They have a lot of flights at CLE, all going to CVG or ATL. Now, they only use MD-88s and even the first flights of the day (at 6-6:30 AM) are full, so, if DL sees that their M88s are filled, why not try and sell more tickets per flight and up the aircraft to a 727 or a 738? UA has done it. Their seasonal loads have gone up, so they introduced their summer 757 service to ORD, DEN.
Now maybe I can get riduculous after my serious question. FedEx and UPS fly A306s out of CLE every day, so we can handle such large aircraft, and you could compare the A306 to the 767 family, so if DL really wanted to reduce their number of flights, have two 763 (or at least 752) flights to ATL and two to CVG and back, and then have maybe one DLX 732 flight to both in like early morning, midday, and late-evening. So, a total of 10 flights a day, about the same as now, and then you have more people to deal with, and possibly add a daily flight to somewhere else as a feeder for the 763 (or 752).
I know that won't happen with other airlines, since they are well, not content with what they have, but accept it. I'm sure if the landing fees were lower you'd see all sorts of stuff at CLE. The gates can handle the aircraft, as a matter of fact the one DL gate, B6, has the markings showing where to stop the different aircraft, L-1011, 757, 767, etc.