I've never stayed at Las Marinas, but have seen it and it looks really nice and close in. As I mentioned, Denia can be pretty crowded, but since you won't be there in August, it shouldn't be too bad. The beach in town is fairly nice. If you go up the coast a ways to the newer part of town, the beach is nicer. Your child will love taking the little train up to the castle. Your little one will see it and be begging you for a ride. Try Fernando's restaurant at the far end of the main beach. However, my favorite restaurant is Mena at Las Rotas. You will need a car or a cab, but it is wonderful food and set on a rocky perch above the sea. We also liked taking the boat to Javea. (Beware if the sea is rough--it's like a really fun carnival ride.) The coast is stunning.