How old is too old???

I have two girls, the oldest one is almost 11 and the youngest one will turn 8 next month. We are a very close family and on saturday mornings the girls love to get in bed with me and my hubby and snuggle and watch cartoons (the cats and dogs get their snuggles in too ) and when my husband is offshore/deployed they sleep in bed with me every night. They begged and begged for their own bunkbed so they wouldn't have to sleep together in the same bed but when hubby is home they go to bed in seperate beds but they always end up snuggling together in the same bed. so my ? is how old is too old for them to be sleeping with me and each other. they have a very strong sister bond and they just love to sleep in bed with me and for some reason they are always wanting to wear my nightgowns to bed....too funny! Just wondering what ya'lls opinion is on this. thanks