I understand that this isn't likely as it has already been pointed out that 3CDC won't give up parking in 84.51 building, but if they could be persuaded would make this more worthwhile and buy more time before any future expansions.
Take the parking in the 84.51 building add it to the proposed expansion converting it to convention center exhibition space. Reposition hotel to allow 84.51 to expand over proposed convention center hall expansion. Would be great if they could activate the proposed convention center expansion at the street level with restaurants and shops while also trying to lure development around the convention center on 5th and 6th with street level businesses as part of any developments.
Finally, add a free downtown circulator to drive traffic around the convention center and provide residents a way to access the rest of the downtown.