I feel like it would be perfect for someone remodeling a large hotel, furnished apartment complex, etc.

Are you buying a collection of condos in one complex (individual titles for 100% of the each unit) or are you buying a collection of partial titles (1 unit's title split into fractions where a group of owners will own the specific unit)?

I am considering a master lease option to purchase a large apartment complex.

I am considering using a HUD 223f loan to refinance a 100 unit conventional apartment complex. 

When purchasing an apartment complex with leases currently in place, is it better to start with all new leases or continue with existing leases until the lease term end?

I recently contracted on a 5 unit multi family apartment complex.

You'll also want to account for your exterior maintenance for lawn and landscaping.If there are any common areas within the complex (i.e a shared entry, hallway with mailboxes, laundry room, etc.) you'll also need to factor in utility expenses for electric and likely gas.Even without all the increases, the property is too much and/or the rents are too low in order to obtain a good return. 

I grew up in a Condo which we now own and I’ve been thinking about buying a couple units within our complex area.

*Thought about small multi-family but seems more complex to down the line maybe.

So, I can renovate any property in the US to move in condition by doing a cosmetic upgrade for $XX depending on the size of the property.This is just step one to get to an offer stage...you'll need to bust *** in due diligence to confirm your assumptions...a great agent can be your best asset here...or your contractor network.Unfortunately, the real solution is a wildly complex algorithm that will only get you marginally better results...remember, acquire properties by going through phases...phase 1 is getting comfortable with an offer based on what you know after the first filter...entering due diligence is where the real work starts.