It appears there is room to add some garage decks in the open portion of the block where the buses used to park. But the additional access ramps might take up too much space from what could be parking spaces. I don't know if somehow the new parking portion could be accessed from the old garage so that its' ramps could be used instead. This might conserve parking spaces. Engineers might be able to design the new garage addition in such a way so that entrances to it might be created by knocking out walls in the old garage to create portals to the new garage decks.
One problem with adding parking decks in the undeveloped portion of the center block is that the some building apartments might lose windows on the north side of the hotel structure. This might affect the desirability of those apartments, or as hotel rooms.
I don't know what kind of structural condition the old Pickwick Garage
is in. It appears that the Pickwick complex is a series of three separate buildings: the hotel, the former office portion, and the garage. See rendering.
Perhaps the old garage could be demolished and a new garage built in its' place that is larger and better connected to any garage portion over the undeveloped surface lot spaces. This would preserve the old hotel and office portions as well as create additional spaces over the surface lot at the SW corner of 9th and Oak, which was the site of the former Palace Cafe
and Gladstone Hotel
If I were the developer, I would purchase the former Insurance Building
from the owner of Abdiana Properties, which has been slowly rehabbing that building. I would combine the Insurance Building with the Pickwick properties to create a larger complex with shared garage. The Insurance Building doesn't appear to presently have any dedicated parking. It is slated to be residential, so it makes sense to combine that property with the Pickwick development and share a garage. Perhaps the two buildings could be connected over the alley.