Road races should be raced in no longer than mile laps. There should be a good viewing section/stadium where runners have to run through (each mile or even 3/4 of mile) so spectators can watch the development of the race. Of course the race would finish in the stadium. You would have to have less runners.
An electronic score board providing information about pace, position, time behind leader, etc. Provide a simple program with a little bio of the best runners.