I hear you!!! I am getting married in Mexico in JUNE...I KNOW I'm going to be hot. I had two dresses that I liked, but I was fighting with myself between the dress I knew was best for the location, and the dress I loved the most. In the end, I ended up ordering the dress that I loved the most. If the dress is something you absolutely love, and you can't get it off of your mind, that's your dress!! The salon I ordered my dress through gave me tips on things they could do to make the dress "lighter" feeling without losing the look of the dress, and it was exactly what I wanted to hear. I will be changing into a dress for my dinner and dancing, so if I'm hot for an hour, it will be totally worth it to have the dress I am totally in love with.
Here is the dress I chose....and i'm not worried about the heat, because I absolutely LOVE it.
Hope this helped!! and good luck! Let us know what you choose