The 51 is my favorite highway in Phoenix simply for the scenic views and convenience. The drive through the Phoenix Mountain Preserves is a nice change from the boring highway driving in this city. If you can, I'd avoid this highway Mon-Fri between 7am-8am (southbound) and 4:30pm-5:30pm (northbound). Those seem to be the worst times. Also, avoid the exit for the 101 west during the evening rush hour. It's a nightmare. My one and only goal in life is to be the Duke of the 51 Freeway.
PS-If you litter the highways or anywhere in AZ, I'll turn your ass in.
Don't Trash AZ: 877-354-8837