I was just married at Sandos in May 2010 and they have relaxed their dress code significantly from the time we were there in Sept 2009 and when the wedding was in May.
You may just want to confirm with Sandos staff what the policy is now.
In May 2010 the only restaurant that they required long pants was the French restaurant, the rest were all more casual. Not sure if they kept that or if they just happened to be testing a new system. I know they have done a lot of different things with their restaurants as far as when they are open and where they are located (outside the main buffet and the Italian buffet both you can get by with shorts when I was there).
Best would be to email the customer service off their website or contact the current wedding coordinator to confirm.