Jennifer,
I'm originally from PR and know the Rincon area well so I can give you a little bit of insight.
The population of state-siders varies on the season. During the Fall and Winter months the "east coast" population spikes but during the rest of the year it drops off dramatically. Just as a rough guess I would say by as much as 70-80%.
Cant really offer much more info without knowing some details.
1. Are you considering moving permanently to PR?
2. Are you thinking of buying a 2 floor vacation home and renting out the bottom floor in order to pay for the entire property mortgage? What would be your plan?
3.Understand the laws of PR are very.....very renter friendly and against the landlord. I know of horror stories regarding eviction cases taking up to a year to evict someone (due to the renters attorney kept filing to extend the court date) and in the end they don't get a dime. Or the owner had to pay to get the person out of their property.
4. Also taking into consideration life operates on "island time" and any job that can be done today will be put off to finished tomorrow and meeting times are mere suggestions, if one says 12noon that could mean they show up anytime from noon to 3pm-- which can be very aggravating for people coming from the states. In addition because you are fresh from the mainland if you need any work done on your property the price will tend to be higher as you will be getting the gringo price. Some may disagree with me but trust me its a fact of life. (its not anywhere near as bad as what expats get in say Dominican Republic or Costa Rica, but it does happen often in PR)
In my 30 years living in PR I have seen a lot of people from the states come thinking they found paradise and leave a couple years later pissed off. That all being said, if you can embrace the quirks of island living, everything else more than makes up for the few aggravations pointed out. And once you have been here a couple years you learn to go with the flow. :-)