Humphrey was the quintessential Cold War liberal. He was a strong supporter of the New Deal, Great Society, War on Poverty, etc. along with being a strong anti-communist. If Humphrey is elected President in 1968, he probably takes a similar policy to Nixon in Vietnam, minus the expansion of the war into Cambodia. In fact, he'd probably follow a similar course to Nixon overall, though I doubt he would have gone to China (politically difficult for a liberal Democrat). Domestically, Humphrey will continue the policies of Johnson. That means more spending on housing, job creation, welfare, education, etc. It's possible HHH makes a big push for a national health insurance plan, but that would require a major legislative push. Overall, Humphrey is one of the easier alternate Presidents to pinpoint. He was a reliably liberal voice on most issues, and would have governed as such. It's unlikely that he could have held the New Deal coalition together in the long run, but his victory would have been a "last hurrah" for FDR-style liberalism.