as far as the states goes-- texas sucks. the midwest usually sucks. the south is weird because it's usaully terrible "get a job u hippy faggot" screaming rednecks but when you do get a ride they always kickdown money/food/hotel rooms.
latin america-- maracaibo, venezuela is the proly the only spot on the planet i'd never return to. it's essentially a petroleum boomtown modeled after 1970's texas. Unbelievably polluted, hot as balls, sketchy ass people, lots of guns, greedy cops, and a smell that makes you wish you were dead. the toughest place to hitch a ride in all of south america. mosquitos by the bushelfull. the kinda place that makes houston seem cool.
obviously your experience in any given town is entirely subjective-- who you're with, the weather, your luck scrapin together bean money, etc. BUT, there are some rad places too. for example: colorado is amazing for hitching (denver is a little tricky). mexico is the shit. rides and kickdowns all day long. colombia sucks for street vending but outside of the big cities people are so cool you have to turn down several free meals/places to stay every day (hitching is tough, though). venezuela has a socialist govt with free food everywhere, drunk people that spend like its payday 30 days a month, and you never have to sleep outside, the people love traveling weirdos. ecuador is a hitchikers paradise. you can leave the capitol city at 3 in the am piss drunk in a group of 8 and be well fed when you make it to the beach a few hours later. in brasil, the people pride themselves on saying"nobody goes hungry in this country" and most hotels will let you catch a shower and feed you breakfast for free. and the truckers are the coolest people ever. spot a trailer with brasilian plates anywhere in sudamerica and you have a guaranteed ride and a few free meals coming your way. squatters rights are off the chain in uruguay. i have buddies that just decided occupy an abandoned town. argentines are a weird group but the have a crazy travel culture and wont let a wanderer go hungry. actually, all of latin america is hobo heaven. learn spanish (and eventually portuguese) and enjoy liberty outside of the ""home of the free".