I want to encourage my guests to dress a little more formally than usual. In my region, it is common for people to show up for weddings in jeans and dirty flip flops. What I have in mind is cocktail attire - a dress or slacks and a nice shirt. I plan to make a statement to that effect on my wedding website, but I don't think that many people will even go to the website. Would putting "formal dinner and dancing to follow" on the invite be a good way to gently convey the level of formality? I think I'd be uncomfortable outright dictating "cocktail attire" on the invitation. I won't freak out if someone does show up in jeans, but I have been to weddings and thought how disrepectful it is to the couple who've put so much effort into making a nice day for their guests.