According to The Demand Institute, a research firm focused on consumer demand, Millennials will spend over $600 billion on rent within the next four years.

@Jim Carson,Better Option is Hold for ever... advantages...Tax Saving: If you will sell, you need to pay hefty tax on appreciationTime Saving: you pick lot of properties and that consume lot of time. doing all again will take your time and energy again.Opportunity: we don't know we are on top yet... look at market in Canada, Australia, China, India... appreciation cycle still continue after 15 years. 

This is time consuming and I'd like to know who others are using for this effort.

Has the seller received any notice of foreclosure, if so you need to head the other way if you can't buy it, this is full of new foreclosure landmines, if no notice has been given then you can proceed on the creative side.If you are acting as an investor, you can do an installment contract, as a real estate dealer selling to a consumer, buyer tenant, you'll have federal laws to comply with, pretty hard to do now.However, I'm more concerned with, what appears to be, the  intent of avoiding the mortgage requirements.

@Amber BarrettCommercial leases have far fewer restrictions than residential leases - essentially basic contract law.   

The realtors say that they need more inventory, and I notice that their seem to be a lot fewer "For Sale" signs in the upscale neighborhoods.

Just keying that many entries would consume days, maybe a week even, every single month. 

My story -As an active real estate agent on both commercial and residential fronts dealing with retail consumers and investors.

She has sold them all and turned to the Independance area where the rents are higher and she has had fewer tenant issues. 

No and I've only thought of it once and that was because a buildable lot in Raintree Country Club (arboretum area) came up...but I still didn't do it.It's too eexpensive, takes too long and way too time consuming especially for an investor and LAND PRICES in any area you should be investing in would be insanely priced.I think its great you are thinking of all options.