Groom Attire

My best friend is getting married in Punta Cana in February, she is struggling with what to dress her husband to be in. Although she will be in a white gown, she does not want to put him in a tux do to the heat but wants him to be dressed up enough so that he does not look out of place next to her ..........any ideas???

The other guys will be wearing colored shirts and khaki pants........thanks for your help in advance!!