Right now most of our investment portfolio is in reits, stocks, index funds.

Glassdoor recently published its recovery index across 300+ cities, taking into account the local unemployment rate, level of job growth, and the change in wage rate.

Dallas/Austin (Above All Time Highs) - http://blogs.wsj.com/economics/2014/12/30/eight-ci...Dallas Home Index (Approx 18% Above All Time High Austin isnt Tracked) - http://us.spindices.com/indices/real-estate/sp-cas...SF Home Index (4% Below the All Time High) - http://us.spindices.com/indices/real-estate/sp-cas...

Index Funds are likely your best friend.

I'm interested in investing in long term buy and hold 2-4 unit properties and my goals are to 1.) have a better investment vehicle than a stock index and 2.) have enough passive income in ten years to retire if I wanted to (although I doubt I will actually want to retire). 

The majority of my money is currently in index funds, but given the success of the stock market over the past 8 years, I feel like it is a good time to try to diversify into some additional real estate holdings.

As sales declined from a year ago, the unsold inventory index, which is a ratio of inventory over sales, increased on a year-over-year basis as well.

If your market only supports a 6% ROI on rentals right now, but the historical return of the stock market is 12%, maybe it makes more sense for you to throw that chunk of capital into a high-dividend paying index fund instead of investing in a rental at this time.

My decision was purely based on research: unemployment going down, migration into area going up, rents going up, prices going up steady (but not sky-rocketing), Case-Schiller Index elasticity and things like that.... then I did my homework with finding the team (realtor/s, property manager, investor-friendly escrow company, other investors, etc...) and started going to work. 

@Jeremy Morton the wealth you accumulate through index funds will be a much slower process versus investing in real estate.