Regarding EWR-CLE-EWR 12/18-19.
If you book two one way tix
EWR-CLE-PIT = $388, get off in CLE, obviously
EWR-CLE = $599 non-stop, $574 with stops
CLE-EWR-BOS = $435
CLE-EWR-IAD = $435
CLE-EWR = $599 ns, 547 with stops
Round trip:
EWR-CLE-EWR = $1115ns, $1112 with stops.
So, you could save ~30% with a two one-way, drop the second leg approach...