The safest and nicest area in Vallejo which has affordable housing varies depending upon your budget, as well as a few other factors. I'd say there's a home right now that I would recommend, but would take a bit of work to make it very nice. With the proper real estate professional guiding you, your options abound. If you were to purchase anything here when this post first started, everything was affordable in comparison to today. Prices have probably more than double since 2010. I spent 2006-2009 in the DFW Texas area but grew up here in the San Francisco Bay Area and have lived here most of my life. I've been in Vallejo about 3 years altogether, and spent a few in Fairfield, but mostly in Marin and Sonoma Counties. Where I grew up, prices are probably almost double or more than they are in Vallejo, and whenever you see higher home prices like that, typically neighborhoods are safer. Once in a while, there are affordable housing programs in some of these higher priced cities, but for the most part your best bargains are here in Vallejo.
I've seen a duplex get listed this week for $250,000 with one of the units already having a tenant in it paying about 75% or so of what a mortgage would be so someone could have gotten into that purchase deal with about $10,000 or so down payment and closing costs, then pull out about $400 or so out of their own pocket and add it to their rental income to pay off their monthly mortgage. I see another home right now for sale for $226,000 or so that needs some work but could be purchased with an FHA 203k rehab type loan and become a very nice place. I have one for sale from it just 3 or 4 doors don that's selling for $400,000. Deals like these come and go, some in better areas of town than others, but it's always best to get a guy who lives and works here to help you make some decisions.
Have you already bought here? If so, where, and are you still in that same place? Please give me an update, I'd love to know how things went for you and how they are now.