What do you think is best for my cat? PLEASE HELP!?

in the summer, I am gone every weekend (usually fri afternoon to mon night) and then i take a lot of vacations (i just got back from an 8 day one on monday and leave for 15 days on wednesday). my cat always stays home and gets vary lonely. My grandfather comes over everyday to feed her and pet her, but only for like 30 min and shes used to having someone with her at night. Do you think i should take her to my grandfathers house for the rest of the summer so that she will have someone with her at all times or leave her at home? shes old (about 12) and has lived wit h3 or 4 different families so i dont want her to feel abandoned again, but i dont want her to be lonely either?? what do you think i should do??