No direct experience, an investor in one of my companies years ago had a "family" retreat in the NVI (Tortola).You'll need to bring $1M+ to play, unless you want vacant land far from the coast.Have a look at the Global Property Guide as a starting place for your research.

It was free but an hour of that was Wayne Gray selling us his $997 Real Estate Retreat that boast financial funders for deals up to a million per deal with 1.65% interest.Couldnt find much on it except this one thread.

I wish I had discovered BiggerPockets.com before I wasted $1200 on a 3-day retreat sponsored by some so-called "gurus" and spent thousands more on their training modules.

That like saying I went to a singles retreat and met 1% and no one wanted to marry me.  

Since you are building several maybe you could market it as a group retreat / family reunion kind of thing... or go for the whole Christmas theme...

I love your goal of one day having a retreat for missionaries, I have similar goals myself.  

Think of it like being a retreat away from the kids.

@Bret Allen We provide the house pest-free and will re-treat if reported in the first 30 days.Our lease has had the term "any additional or periodic pest control is the responsibility of the tenant" for at least the 11 years I've been here, and it has been vetted by our attorney.I understand your opinion may differ, but I would rather have a tenant raise the issue of being responsible for their own cockroach problem (we do SFH, so neighbors don't play in) than being named in a suit for damages because somebody had a fatal reaction to our pest control vendor's choice of chemicals. 

Watch how fast they retreat.

I've done many, many deals in San Diego and still own well-performing assets there as well as a large private retreat/ranch in North County.