Since you mentioned tenants, I'm assuming you're looking at buy-and-holds and not flips.
In general I think the returns for multi-families (and SFRs for that matter) are going to be pretty poor in the suburbs. When I see multis come up outside of the city proper they are almost always priced high, more for an owner-occupant who wants to shave something off of his/her mortgage than for investors looking for cash flow. That's not to say it's not possible to find a deal, I just think it's tougher outside of the city.
For my first property, I wanted to live it in, so my criteria was skewed towards things that I wanted at the time. But since I was going to be living there, the neighborhood had to be fairly decent. It just so happens I bought right without really knowing what I was doing. For the 2nd, I had educated myself much like you're doing and looked for a solid return, again in a neighborhood I was comfortable with since I had decided to self-manage. Both are within city limits.
Best thing I can recommend is to look at lots of properties and run lots of numbers. Figure out what gets you excited. That's when you know you've found what you're looking for.