I have some experience with renting retail space. 

You can certainly fix up your own spaces (I'm personally finishing my own basement); however, there is an opportunity cost associated with DIY work.

Many would pay $4k a month for a shoebox that feels brand new vs a bigger space that is outdated or not too clean. 

Higher end interiors, outdoor space, basically any upgrade raises the costs.  

There are still hard money lenders that are active, but there has been a huge push over the past few years as more and more people flocked into this space.

Although places like WeWork and such may have not gone about the flexible work environment model in the correct way there is certainly something to be said for still wanting an office space, but a more shared or less permanents lease model would certainly be attractive to many startups....including myself! 

Outside of this, I've been learning a lot about the commercial multifamily space, and am positioning myself to syndicate an apartment building soon. 

When searching for a rental, I am typically only looking at properties with at least 3 bedrooms or enough space for a 3rd bedroom.

I would say, from a leasing perspective, unless you're in a downtown core type area, the retail space is harder to lease.

However, many fail to recognize much less understand how a small confined or even large space without adequate ventilation/dilution air can result in death of people subjected to elevated levels of carbon monoxide in the air they breathe.