My main wishes have been mentioned, so I'll just elaborate a bit.
In the inner cities, I'd like to see "complete streets" that are totally redesigned to put cyclists, peds and buses on an equal (at least) par with cars. Not just sidewalks, bike lanes and bus lanes, but more innovative approaches where the whole street can be used by everybody.
In the suburbs, I'd like to see a return to grid street patterns with 90 degree controlled intersections. Get rid of the merges, diverges, complex intersections and yield signs. Back to the square!
In rural areas, I'd like to see wider lanes and good paved shoulders that are maintained, swept and plowed regularly.
Minor point--I'd like more public drinking fountains all over the place.