We will be down in a week and it will be our first time in San Pedro during the winter months. Are shorts and sandals going to be comfortable for the evenings or should we bring long pants? Trying to pack as light as possible.

Also, does anyone know if either of the airlines have "tourist" flights that might fly over the "Blue Hole" and other southernly cayes.

Shorts and pants, you'll need both.
Shorts for the days, but some evenings are cool enough you will want pants, other nights you'll want shorts or skirts. Have a wonderful winter in Belize, jealous....
I'll be back in May!!!

I agree with ke on the long and short pants recommendation.

As for the fly over Blue Hole and other cayes, you might have to do a private charter for this with either of the airlines, Maya Island Air or Tropic Air.

Tropic used to do it at 10:30 daily for $99 US pp. I'll check if it's still operating.

Yep, as far as a few months ago (hummm could be several by now ) you can indeed do a "fly over" a lot of things! I would TOTALLY recommened it too!