Washington should not become a state, because (as I pointed out) it's just a medium sized city.
Statehood is the only real option left. Retrocession is not feasible, since no existing states want
DC to be a part of it. And DC's current status is unacceptable as well, because DC residents have no representation. Something must change. If there is no other option but statehood, then that must logically be the way to go.
And to be honest, who the hell cares how big DC is? So it will become a really small state. Big deal! At least its people will have rights and representation. That's all that matters in the end.