Start some kind of store or service in there which could possibly make much more money, or play it safe and just take the rent money from a new tenant?

Is it safe to say that someone looking for buy and hold rental properties would be less concerned with timing the market versus finding good cash flowing deals and dollar cost averaging into the market as it cycles? 

Neat, tidy, safe and to code.

I want it so that my personal assets are safe from liability.. 

Any improvements done to those rental units (depending on safe harbor and tangible property regs- but lets assume big items that require capitalization) are depreciated 100% at 27.5 years. 

I personally think this is a safe solution.

Let's also assume this plays out across several properties, so we can safely utilize a market cap rate of 7%.Assuming your building is identical in terms of unit size, quality, location, etc - You have 14 units with market rent of $1k/mo ($168k/yr PGI). 

Pot or not growing things inside is completely safe and actually rather therapeutic.

I like to have little leverage as I like to play it  safe - However I want to expand my investment portfolio and this deal is exactly the type of investment I like.....  

For example, Dave Ramsey advises people their investments will grow at 12%, and they can safely withdraw at a rate of 8%.