How much more challenging is getting into cash flow businesses (like a laundromat) than typical investment properties?

I don't mind those examples, Michael.

For example the contractor had to replace roof or do other repairs to make the property rentable and I spent 2 hours talking to the roofing company and plumber? 

@Steven Rago legally, whoever shows the property has to be a licensed agent.You can try to play games with that and have a handman allow "access", but it's a BIG risk.So that leaves agents & PMCs.You have two choices with agents:1) Pay per showing: since any agent can show a property, find the cheapest.2) Pay Listing Fee: typically 1 month of rent to put in MLS and place a lockbox so any/all agents can show.We do NOT recommend allowing agents to screen applicants - it's a conflict of interest!

Others have told me for example stick to all white and gray while others have said to go crazy with colors and make it UNIQUE…  thoughts on modern vs chic? 

You can hear real-world examples of how others have built their investment portfolio and (hopefully) learn to avoid their mistakes.4.

Typically very little ROI, and not much appreciation either.

For example, the city of Palm Springs has a hard-limit on the number of STR rental permits it allows (and it has a huge "wait list").   

Typically these are not "taught" but lessons learned from experience. 

Looks like you're in great company, your dad may be able to help you avoid some of the typical stumbling blocks that new investors encounter.