If you will be in a lower tax bracket this year than when you plan on retiring, it would be worth it to look into (always do your research in many places) converting it to a Roth.       

My husband is retired from a career in mental health case management. 

I don't like putting rentals into retirement funds.

It's a retirement account and there are special circumstances where you can take out the earnings early like my situation or school expenses, but for the most part you have to wait until 59 1/2.

Easy to start, great future with lots of profit and paid retirement perks.

My "why" for getting into real estate investing is actually because I want to get back into competing with 1-3 mounts, and ultimately being able to afford a small horse friendly property that I can bring my critters home to for rest/retirement.

I have read and heard about using a self directed retirement account to invest in real estate.

Baby boomers are retiring and more tech-types work from anywhere.My personal preference is residential real estate, so from your list I prefer Multi Family

The majority of insurance companies that I worked with during my 34-year insurance career (I'm now retired) had NO interest insuring this type of exposure. 

Look at the Macau Floating Casino. https://www.tripadvisor.com/Attraction_Review-g664...When I was growing up in the San Francisco Bay Area the hippies started building house boats across the Golden Gate Bridge in Sausalito.http://www.sfgate.com/homeandgarden/article/Sausal...I have some small houses that I built in the State of Rio de Janeiro, Brazil and a small farm where I wanted to retire.