I'm making my own dress, but...

[elmophobeccad]

Alright, so my fiancee and I are getting married, and I'm making my own dress, for my wedding and also as one of my projects for school. The only thing is, we are getting married on the beach. The dress is already going to be short, but I want it to breathe easily without it looking bad. Cotton doesn't look formal enough and I don't know if taffeta is going to overheat me.

Any suggestions?