@Alexander MonninThanks for mentioning me Justin and Alex.Justin, you have fulfilled my first requirement in Investing.If you plan on living for a long time in a very high quality City in a location which is desirable and will continue to be desirable, you MUST buy your primary residence there or you may become priced out eventually.That has happened to a LOT of my friends and relatives.Now you can live in Brooklyn without the fear of having to move because you cannot any longer afford the rent.The next step in your strategy depends on what you need.If you were like me when I started out, house hacking in Brooklyn 20 years ago, but with a very good Salary, there was no point in making anymore cash flow than my professional job.The great thing about Appreciation plays is that you don't pay Taxes on the Capital Gains until you Sell.Even then you can do a 1031 Exchange.If you can keep the properties until you die, then you never pay taxes (but your Estate might).There is even a really great Tax Loophole which will allow your children to inherit your Property Tax Free and then step up the basis!

Exterior Siding: Vinyl siding does not stand up well to weed eaters and children bounding a ball off of it.

The tenants work all kinds of crazy hours and have small children in the house which makes doing any repair work to the units difficult to schedule.

Some title them with their children.    

The first tenant being a student would probably prefer the place to be more peaceful than what is happening with children in that other unit.

Can I fire my children?) 

Also find out if they will have grand children visiting very often.

I pay child support for 3 children.

However I am single with no  children and I cannot count the frustrations I've had with some agents and bankers.

The only way to reverse that trend would be something on the scale of an extinction event, like Yellowstone blowing.Second, the children of the baby-boomers are even more prolific than the parents of the boomers themselves.