Most all inclusive resorts, and cruise ships for that matter, have resort casual dress codes in place for their restaurants and main public areas. Guests need to be aware of these rules and pack accordingly so that they don't miss out on any fun on their next family vacation.
All inclusive resorts and cruise ships offer both buffets and "ala carte" dining. This word "ala carte" tends to confuse people because meals are suppose to be included with both of these types of vacation packages. In this situation, "ala carte" dining describes a restaurant with full waiter service verses a buffet where guests serve themselves. Often these restaurants offer some type of themed or ethnic dining choices - Italian, French, Asian, Mediterranean etc.
On cruise ships, meals for guests are included in the main dining room or at the buffet. Cruise ships usually charge to eat in one of their specialty restaurants. All inclusive resorts generally do not charge for their "ala carte" dinning. Some resorts may limit the number of times per week that guests can eat in specialty restaurants by offering a limited number of reservations. Some all inclusive resorts may offer a high end adults only restaurant where guests are charged a service fee for say lobster or a multiple course wine pairing menu.
During the daytime for breakfast and lunch, resorts and cruise ships usually open the buffet for self serve meals and one dining room or restaurant for meals with waiter service. In addition, there are usually snack bars available for a quick coffee, a slice of pizza or a burger. The dress code during the daytime is generally casual. Guests are either planning to spend time at the beach or pool or they are off to do some activities or sightseeing. This means you can wear a dry bathing suit with a cover up or shorts, t-shirt or exercise gear, sneakers and flip flops for meals.
Evening dinner time is when the "resort casual" dress code really applies.
Now if you want to remain casual, the daytime dress code will apply to the buffet. Guests can wear dry bathing suits with cover ups, shorts and sandals pretty much any time to the buffet.
If your family is planning to dine in either a main cruise ship dining room or resort specialty ala carte restaurant, then your family will need to dress accordingly or you will be refused service.
Adult men - should wear long pants and a collared shirt along with closed toe leather shoes. This could mean a sports shirt or a golf shirt and a pair of khakis. Generally, no jeans, baseball caps or sandals.
Adult women - Dresses, skirts, capris, pants with a nice blouse. Again, no jeans. Women can wear leather sandals or heels but NO rubberized flip flops (even if they are covered with diamonds).
Teens - Should dress according to adult guidelines.
Children - Younger children should look neat and tidy along these same lines with no beachwear. rules are a bit more relaxed for kids footwear.
Some cruise ship sailings still offer a Captain's dinner, formal or elegant night in the main dining room. "Cruise elegant" dress means dress slacks, dress shirts (with tie or open collar) and sport coats (optional) for men and cocktail dresses, pantsuits and elegant skirts and blouses for women. On elegant nights, passengers may choose to dress more formally in suits and ties, tuxedos or evening gowns, but that level of dress is not required.
Many families do enjoy the opportunity to "dress up" and use it as a photo op. Photographers are on hand at the entrance of the cruise ship dinning room and will take family portraits on speculation.
In addition, all inclusive resorts also have the same photography services for the asking. Families will often dress in a theme (Hawaiian shirts) or in the same color palate and arrange for a photo shoot right before dinner or at sunset.
Ultimately guests can choose to be as casual or dressed up as they prefer on their vacation. If you're the type that wants to stay in shorts and flip flops for your entire vacation then that is your choice. Just know you may be limiting some of your dining choices by not following the dress code.