@Dave FrederickIf you plan to sell the properties - you want to have a discussion with a CPA to see if there are ways to defer the payment of tax.There are unique tax laws when it comes to US citizens who live abroad.

We may have a unique opportunity here for section 8 with so many low income earners, high rents, and a state that panders to those individuals.

This one is a stretch because every project is different. 

I’m in three different markets at the moment and each one has its own unique opportunities.

There are many unique tax laws/strategies when it involves real estate(Depreciation, 1031, cost seg, etc).There are some states that have very complex state tax laws(CA and NY come to mind) so if you live/invest in one of those two states, you should try to find a CPA in those states or atleast someone who is knowledgeable in those areas.If you do invest in a state other than the state you live in, you may be required to file a non-resident state tax return. make sure to work with a CPA who understands multi-state taxation.

Lots of cookie cutter, lower priced houses are more likely to be rentals than if the house is surrounded by custom built unique houses.

of lobbying by the airline industry which came as a direct result of tons of bad PR by the airlines that put their foot down in a few unique cases that "blew up". 

There is a piece of thick vinyl stretched and adhered under every drain in a cabinet in my places.

I'm interested in finding all of the multifamily units with 4 or more units that are 8 miles or less from the stretch of I-95 between Richmond and DC.I've looked at Realotor.com and Zillow and I have to enter each city or zip code, and i don't know either for the region I'm interested in.

However, I was wondering if there might be something I am not thinking of when making these estimate that could be unique to the Baltimore market or just any advice or experience others have when estimating these expenses vs. what they actually incurred over the course of owning a rental.