Newbie. Tell me everything you know.

Ask questions and we will answer. Not writing a novel.
One advice, learn Spanish.

For starters, do you have any advice on areas to concentrate on when looking for investment property.  Yes, we will be using it too but very minimally.  Mainly we just want to pick an area most appealing to short term renters (AirBnB, etc.).

Well, my best guess for short time renters would be near the airports.  That of course is San Juan and Aguadilla.

Not my preference (San Juan) as traffic is horrible.  😤

Investment property can be many things. But I will assume you mean property to rent short term Airbnb like.

A lot depends on the market you are looking at.
You have people looking for the Tourist environment, a condo or house close to the beach in Condado or Isla Verde will do
You have people interested in night life and a little history, Old San Juan can provide that
You can people interested in Ecology and getting back to nature, properties around El Yunque can provide that.

Each of them has to be market differently and to a different group.

I've recently been in touch with a real estate agency that suggested buying in Isabella for the investment opportunity.

I am by far no expert as I have only lived in PR for almost 3 years but I would definitely suggest going with short term only as you mentioned.  From my understanding, it is very difficult to get non paying, long term renters out of a property here in PR, particularly if they have children.

Any of the more popular tourist areas would be best.  San Juan & immediate surrounding areas as well as Rincon would be good choices but I would think that Rincon might be more seasonal (winter being higher season catering to surfers)

We were looking at the possibility of purchasing investment property for short term rental and we were focusing on the San Juan area.  After hurricane Maria, we wanted to let the dust settle to see how things in the rental market shake out

Hope something here might help.  Good Luck!

Brian