This is a very broad question, but Dallas/Fort Worth area is a great place to start. It looks like you may be a little late to the party in that area now, but there are some good deals hidden there. You can still find cheap properties (may need a little work) that could demand a high enough rent to meet the standard rental rules.Great economy, with a high presence of health care and aerospace companies. It also has nationally acclaimed higher education.
What areas of the country are you looking at?