I think American Canyon is a great investment...even now. There are great schools in American Canyon and a newer high school which attracts people from all over. Demand for both purchases and rentals has been strong for the last 2 years. Find a something at a good price with sweat equity and go for it!
American Canyon is a combination of older homes and new subdivisions, so prices will vary greatly. More important is the strength of the rental market, which is moderate compared to the stronger markets in San Francisco or Silicon Valley. It's impossible to predict a rate of return accurately unless you have a specific property in mind.