My daughter is a climber and love gymnastics, so I got her a gymnastic bar. I love it because it's foldable and sturdy, and it fits in her little playroom. She's 9 years old now but still plays with it. My 18 months is starting to love it too! (Kids Jungle Gymnastics Expandable Junior Training Monkey Bars Climbing Tower Child play Training Gym Pink).
My 4yo boy loves tile magnets, any art and painting activity, puzzles, hot wheels: cars, tracks and launching stations, bike, scooter, kites at the beach is one of his fav. He also likes everything his older bother has LOL