I tend to think that social issues should be handled on a state level, such as gay rights, abortion, and legalizing drug usage.
You are correct, however, that a certain level of cohesion is required. There are many things that could not be managed without a strong federal government. I just think that sometimes the power of the federal government outweighs that of the states by too much. Likewise, the power of the states shouldn't outweight that of the government by too much. There needs to be a balance, because each has their own jobs to do.