Guest attire

I am planning a DW in a resort in Dominican republic and am super excited about the gorgeousness of how it will all look in my photos.



Yesterday I had 2 guests ask me what they're supposed to wear, one even asked if they were supposed to wear white because they see resort photos with everyone wearing white. While I shut that one down immediately stating I would not want ANYONE wearing white at my wedding, I had no idea what to answer when it comes to what guests wear.
I have only ever been to one wedding that was outdoors in a hot climate, but I have never been one to notice people's clothes and for the life of me, asside from what the couple and the officiant were wearing, I can't remember a single outfit!
I don't want my guests to be sweating and uncomfortable, but I also don't want anyone in shorts.
What do people wear to these things?!?
To the wedding I went, I wore a spaghetti strap long "beachy" dress, so I'm guessing women will have an easier time figuring it out, but I have no clue what men wear. Send help!