there are heaps of states are good for studying or TOEFL preparation. It's all depends on place you want to live in, Cold or warm, expensive or cheap, big or small city.
when you want to collect information about any place you need to be more specific.
All the best
Here are some warm states, If i wasn't wrong (from my background) Arizona, Florida, Texas, California, New Mexico, South Carolina, Tennessee, Louisiana
About the Standard living, AZ, TN, TX, Louis.. are not expensive as my friends are there !!