Now I'm guessing they're not Sabals - I really don't know. Maybe Yuccas?

I've passed by this area as well and they are definitely Yucca Recurvifolias. They are very very commonly planted in NYC (the most common of all the yuccas and one of the more common landscaping plants in my neighborhood), but they are only for zones 6b and up so they are relatively subtropical!
-Alex

Thanks for the identification, Alex. They caught me by surprise and definitely added an extra tropical feel to the warm weather.

Cool to see. I wish somebody sold trunking yuccas at a reasonable price. I'd try them again here. I have one of these yuccas that doesn't really do anything, doesn't grow, just maintains after dying back about 6 years ago from a cold winter.