If you spend time at the resort(including pool), I would say go deluxe-but one of the "cheaper" deluxe. Animal Kingdom Lodge is amazing! It's a great place to take kids. Along with the Wilderness, it is the cheapest deluxe. Even if you don't pay for a room with a savanna view, you can see the animals as you walk to your room through the hallway. Also, there is an observation area just outside the lobby. I'm sure children ages 5 and 12 would just love it! Also, the restaurant Boma is a buffet with plenty of children's foods, but they could try others if they chose since it's a buffet. You said you have been to Jiko, which is excellent as well! The pools are definitely better at the deluxe resorts. However, water is water. The kids may not even notice. If you've stayed at Disney before, you know their rooms are smaller than most hotels. The deluxe hotels are definitely bigger. There's more space to move and get ready. If none of these factors matter that much to you, I would go with a moderate. I would also consider looking into a suite at the new Art Of Animation value resort.
As for your question about what special events you could splurge on, I would recommend a reservation at Cinderella's Royal Table. Be sure to get a reservation as soon as available because it books fast. It is a character meal with lots of princesses, except it's actually inside the castle and better food than any of the other character meals. You could accompany this with a visit to the Bibbidi Bobbidi Boutique at the castle(reservation needed, as well) earlier that day. Although very, very expensive, they will make your daughters feel like princesses! To adults it may seem overrated to pay so much to get a child's hair styled, but what little girl wouldn't die of happiness to get their hair done by the same people who style Cinderella's?