Well, at our house we are all about the girly stuff! DD3 LOVES dress up clothes, baby dolls--which of course must have beds, high chairs, etc., My Little Ponies, etc. Princess castle, and dollhouse, and play kitchen all used every day.
She also loves to play with her brother's (DS5) Rescue Heroes, and loves to build with her Duplos. They will both sit for hours with books...but neither one likes the LeapPad much (

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They also have a huge collection of small animal figures that they both love to create elaborate scenes with and play for hours with. They sell these sets at most upscale toy stores, or "teacher" stores for a few dollars each. This is so popular with my two that it's what DS asked Santa for for Christmas two years ago--and have been regular stocking stuffers ever since. They also sell these at the zoo--great cheap souvenier that you don't mind dragging home--just adds to the animal box.
PS--for the above poster that mentioned the pony amusement park--it looks really cute, but ours is dissapointing. We got it for a gift, and DD was soooo excited. I don't know if ours is made poorly or they all do this but ours won't stay hooked together very well-- we finally added duct tape in the hopes that it would, but DD lost interest in a toy that is so hard to play with. Hopefully they are not all like that and we just got a dud.