I can't be much help sorry, but suggest that you email Samoa Hotels (see link above under Useful Information) for some options. They are in the Visitor Center in Apia and specialize in accommodation.
One place I really liked on our last visit (although we didn't stay there) was the new Taumeasina Island Resort really close to Apia. However you make a good point about swimming pools not being fenced, they have two pools and I don't think they are completely fenced, there is also direct beach access (their web page has a good pic of the pool and beach).
Taumeasina Island Resort is also modern in design so if you wanted a more traditional look it wouldn't be what you were looking for.