Lola likes to climb inside anything bag or box-like. I even found her huddled inside my roommate's purse once. Whenever I look inside a bag to see if she's in it, she always does this shifty look, like she's hoping if we don't make eye contact I won't be able to see her.
MowMow loves boxes, but only newly arrived fresh boxes. Once he's rubbed on them, played in them and slept in them they become old and he wants nothing to do with them. If I order him gifts from online he's way more interested in the box it came in than the gift.