-Ban personal motorize automobile from downtown between Willamette and 405.
-Leave arterial roads for commercial vehicles and repave smaller streets with brick, cobble stones, or some other nice bike friendly surface.
-Put in moving sidewalks.
-Buy 25,000 Gingers - free to use downtown. Oh yeah, they are called Segways now. Maybe get some golf carts too.
-Build huge underground parking structures under East Bank and Goose Hollow.
Use left over money to attract green, creative, alternative energy, tech, bio, and other businesses to come to Portland.
Also figure out a way to utilize the River better. Look at this picture for example. Venice has a lot of boat traffic too.
Lastly, since I'm the dictator, I get to issue passports and ban anyone from my Portland utopia.