DD is turning 4 next month (and we have some long trips coming up) and we're thinking of getting her one. I'm debating between Leapster Explorer and Vtech Mobigo. Anyone have experience with these systems? I've read all the reviews on toysrus, target, and amazon, etc but looking for some from you helpful moms too! Also, specifically, wondering how much I can expect to spend getting games and books to keep it interesting for her. TIA!