If Airbnb is an option for your spare bedroom then that's great, personally when I first started I didn't want to have to deal with the in and outs of people and also making my place aesthetic enough that it would rank well on Airbnb so I went straight to long term rentals but if you want to dip your toe in the water it could be a good option if shorter term tenants make you more comfortable. 

However, I'm new to this and unsure of the best way to structure a deal like this such that it would be appealing and a "heck yes!"

I just use CMA's from my realtor to appeal.

That might have gone down for a whole host of reasons but it usually decreases when the owner appeals the value based on condition, a recent sale or appraisal, etc.

We purchased the property for $21,000, invested $25,000 in renovations to modernize and enhance its appeal, and sold it for $55,500 on 03/29/2022.

She's picking pretty expensive places to live though so not as appealing as your deal! 

Nothing crazy because I think you have the right aesthetic for the setting, but maybe some fake plants with colored pebbles, bed scarfs, hand towels etc can go a long way to add some life.

It seems hard to find any property these days that will meet the 1% cash flow rule in the US, so financing at 6-7% and not cash flowing doesn't appeal to us as a strategy - but is there something we're missing here where we should definitely lever up?

It's a magnet for both tourists and business travelers.Brickell: A luxurious enclave known for attracting affluent visitors and business travelers.Midtown: A vibrant, upcoming area appealing to younger travelers seeking a mix of local culture, shopping, and dining.Given your budget and the goal of purchasing two condos, investing in a combination of these areas could optimize both appreciation and rental income.

For background info, this is going to be a rental to students at a local grad school who will prioritize function over aesthetic.