CLE is a free-for-all right now. UA still has a United Club (I remember when UA called its lounges the "Red Carpet Club") but only flies to ORD, DEN, EWR, IAD, IAH and one daily RT to LAX and SFO. AA seems to have more total flights than UA, as they fly many of their old USAir routes as well as to AA hubs. DL has five gates and WN has six gates in concourse B. Frontier operates out of the A gates (which are to the right of the TSA pre-check exit). J6 and Sun Country are also there. There appears to be a vacant airline club near gate A5. Delta uses one of the A gates, usually for the last flight of the night from ATL and one of the first flights out in the mornng (there are a number of empty or shared gates like this in A.

The city of Cleveland, which owns the airport, has hired the same consultant that worked with the Kansas City government to build the new terminal at MCI, and has indicated that they may be willing to spend as much as $3 billion on a new terminal (the airport has quite a bit of land for this, as the current terminal is tucked into the northeast corner of the airport property. Portions of the CLE terminal date back to 1955, with concourse B added in 1983 (there are plaques in the airport that commemorate these dates).

Then you have CAK, which is no longer served by DL, but where Breeze and Allegiant operate.