looking at the new bus routes, it seems there are three lines running down park st to downtown, with a weekday cutoff time around midnight. One connects through riverside to murray hill, another to avondale, including decent weekend service.
Then there are two lines down Riverside Ave. One goes through Stockton in Riverside, the other runs from Lavilla to Riverside and Avondale. But neither goes to the downtown. These end a little earlier in the night.