Jennifer Wilson made some great points, and I'll also suggest the most informational route you can take will be to reach out to multiple Short Term Vacation Rental management companies and ask them for their opinion on any particular property, or ask if they have any rentals in a certain condo building/neighborhood and how they perform. They are a goldmine for information and can tell you which of their properties the best occupancy rates and why, what their gross rental income average is for any particular area, and which amenities are most vital to maximizing your rental income potential during the prime rental times. There are a great variety of rental management company options along the Emerald Coast Beaches, it's a competitive market, so it should be fairly easy to get more than one opinion on the different HOA's, which are most agreeable, and who has the most reasonable fees vs. amenities available. Several of these rental management companies have in-house real estate brokerages as well, so it would be wise to consider their agent's interests when weighing their opinion on other rental management companies in the area. My recommendation is to stick with someone local, as it is very difficult to find and retain good cleaners, maintenance personnel, etc.
I'd also agree that 20% is the average cut for most STR management companies around here, but as usual, everything is negotiable and it depends entirely upon the property and how easy/difficult it will be for them to help keep it rented. Some require more advertising and repairs, which they will obviously take into account when offering projections and rental program numbers.