Welk might be a little closer, but I would recommend staying at MarBrisa or Grand Pacific Palisades. They are both about 25-30 minutes from the Wild Animal Park, but they are close to everything else. Welk's location is much more secluded and removed from dining, stores, beach, etc. Both MarBrisa and GPP have tons of free activities for the kids. While MarBrisa doesn't have a designated kid's pool, my kids love their Super Pool and all the activities around the pool (shuffleboard, pool, connect 4, and ping pong). GPP has a kid's pool and a great kid's water play area with water spouts and a small water slide. My kids loved it when they were 5 and under. Both resorts are right next to a huge, upscale outlet mall and are about 3 minutes (by car) from Carlsbad Beach. If your kids are interested, Legoland is adjacent to MarBrisa. In fact, MarBrisa has their own entrance to the park, which is very convenient. GPP is just on the other side of Legoland as well. My family and I have always enjoyed our stays at both resorts.