If you do end up needing a new roof any time soon, ask about retrofitting ridge vents. We did that on our house (Houston, so very similar humidity/heat situation), and it was pretty easy for them to do and didn't add a huge amount to our roofing bill but we have a very plain roof line with only two basic joins along the peaks. We originally had only soffit vents and a 1 motorized vent fan on the roof, which wasn't working and we had them remove, and there was a huge difference in our bills (and the house stays noticeably cooler in the summer) once we installed the ridge vents.