Has anyone purchased a mattress for a Pack 'n Play? Our LO currently sleeps in his PnP in our room (until he just joins us in our bed), and he hates the thin, cheap playard pad that came with it (can't say I blame him). He wakes up within 30 minutes of being laid down, and he used to sleep through the night in his bassinet. I'm looking into buying either a 3" or 5" mattress for it. Any recommendations for a PnP mattresses from mommas who have them? We have a Graco Pack 'n Play. Thanks in advance!