Rivnuts from Homestead,PA on 2/20/2022 11:38:00 AM:
A couple of thoughts come to mind regarding your question.
There are some hostels in DC that you could consider if you are a fan of such. They are less expensive than the hotels in the area and most are within easy riding distance of the train station.
Secondly, you might consider creating an itinerary/schedule wherein you could make it to the train station in DC just in time to take the train back to Pgh. Depending on where you make your last overnight stay before DC and what time you left there you could catch the 4:00 PM train back to Pgh and avoid staying overnight in DC altogether. Upon arrival in Pgh you could check in to one of the hotels near that train station to sleep and clean up. Just a thought.