Beach wedding dress idea

Hello,
We're getting married on the beach in march, so it will be quite warm (hopefully). Therefore we don't expect male guests to wear a full suit , however we would like our male guests to wear at least a trousers/suit pants and a nice shirt - no jeans and no shorts. I think ladies will dress appropriately anyway so I'm not too fussed about that. now I'm considering what style of beach wedding dress will leave an fantastic impression on my guests ? you know wedding plays an important role on the memories of romantic so I think I will pick a satisfactory beach wedding dress to complete an unforgettable wedding ceremony! dose anyone have a good suggestion about my spring beach wedding dress
How do I give people some indication that this is what we'd like (without coming across as being too forceful lol)? I read another thread on here which referred to 'beach formal' - what would you wear if you read this on an invitation? Can you think of anything more appropriate?