One of my friends who is in real estate also said the same thing, never regretted keeping a property but always regretting selling the ones she did. 

I want to either leverage this to lower my rent to inadvertently pay for a storage unit in place of the basement, actually gain basement access, or keep it in my back pocket as there is a small chance my fiance and I want to break the lease early and this may be grounds to do so. 

I'll definitely be sure to keep that in mind.

Now that multifamily is fully rented but not sure I want to keep it just as a rental, especially with all the equity it has.

Keep crushing it bro 

Keep in mind that you could separate it out in different ways, for instance, framing, HVAC, flooring, instead of the way I do it.NOTES: The goal is to sell to an owner occupant.

A Bookkeeper can set up your Accounting system, sync your bank accounts and would be able to work with you to make sure everything is being tracked correctly and you can keep an eye on your balances.Let me know if you need any help with your Books, I would be happy to have a chat.Otherwise, QuickBooks is the most common Accounting Software and I set up all my clients with a BOX account for document storage, since it is free up to 10 GB. 

Keep up the fantastic work, and feel free to reach out if you ever want to bounce ideas or discuss potential deals.

Keep communication clear, ask loads of questions, and make sure you're on the same page.

I'd go with a flat to keep things simple.