I see a lot of amenities you recommended as amenities that increase the quality of stay which leads to a higher guest satisfaction but doesn't really affect my return.

Are you looking for higher cash returns, greater appreciation, or a good mix of both? 

While I do believe that some of the posters on BP are able to do a quality job self managing their portfolio of STR properties, they are spending a lot more time doing it than they’d like to admit.10 years ago in many markets STR provided outsized returns.  

Analyzing an investment with the Cash on Cash return makes more sense to me.

I always recommend to make even a little passive income from a rental after all your expenses, lets be honest you put a lot of effort into this rehab so you should reap a little return.

Here's the deal: You don't need to withdraw and return the current security deposit just to collect the additional $100.

Thus, your return would be about 11%.

My goal is to diversify with an investment that generates steady cash flow, even if it requires a larger upfront investment and lower overall returns. 

There are not a plethora of 'home run' STR's that are going to return in 2-3 years but there is significant value and definitely properties that will return 20%+ COC and definitely several dozen that are obvious values in their own right, and will absolutely carry all operating costs. 

Find an older one who'd rather sit back and get the interest than the higher return higher involvement of another flip.