Lord have Mercy! What should i do?

My wedding is on the beach in June - PNW beach - NOT tropical) i wanted beach attire for my groom and his BM but they dont like the style so i suggested khakis but they are weird and my FH is 6`6 and they look goofy on him. Should they just go w/ a Tux? its about the same price but i dont know if that would clash w/ the whole beach theme. My dress is very flowy semi- formal, has alot of beading w/ crystals and pearls but it looks like a dress that belongs in a beach wedding. What do you think? Thanks!