I'm a project manager by career, so I know with proper preparation, anything can be successful.  

It is possible to be successful in either - it depends on your skillset, your goals, your time and many other factors. 

With HMLs and cash in place, it sounds like you’re set up for success as you move into BRRRRs and multi-family investments.

The one you can scale.I know successful business owners in the fitness industry, tanning salons, real estate, window coverings, maintenance, billboard, ATMs, etc.Generally, I would be skeptical of jumping into a business based on YouTube videos hosted by and featuring people that are likely primarily trying to sell you their respective courses.Small businesses can indeed be great investments, but they are hard.  

We value quality time with our family, are eager to explore the world through travel, and aspire to build a successful life and business together.

You would need to invest out of state since Sj does not have the properties to do a successful BRRRR. 

Which specific one have you had success with?

Generally the time horizons are longer and you need deeper pockets.If you have already had some success in SF rehab, moving to apartments is not as different as moving to development.

Go flip, run the numbers and even partner with someone, a mentor if need be to really get you started on the right path to success!  

While it's not absolutely indispensable and many have been successful without, you'll maximize your chances of success.On another note, @Sebastian Papworth is right about the fact that many more tourists than usual are visiting Europe this summer.