Joe Hooker was fired as AoP commander, but he never lost his MG rank. You are right that he got further assignments out West. Burnside is another good example. After Fredericksburg, he retained his rank, got a command in Kentucky, and did well in the Knoxville campaign. He came back East for the Overland Campaign, which created an issue because he was senior to MG Meade. So his corps reported directly to LTG Grant and was not technically part of the AoP for the campaign. (Later Burnside agreed to wave seniority to serve under Meade directly... something other union generals refused to do.)
It doesn't help that Union ranks were a bit of a mess, given Congress allowed only one LTG.