I took my 3 cats to my parents house for 5 days the christmas before last. It wasn't that happy a time for them to be honest, but the youngest was only 5 months old and I didn't want to risk leaving him with my absent minded housemate who doesn't normally do anything towards the care of the cats and works very funny hours. She would never have remembered 3 meals a day and to let the older cats out, but not the young 'un and to shut them all in at night.
Anyway, it was a 2 hour journey and the older 2 were ok in the car in a big carrier together, but the youngest was quite stressed and pooed as well as being sick in his carrier - not a very nice fragrance in the car
Once at my parent's house they basically hid in one room for the whole 5 days unless it was just me in the house or at night - then they were happy to come out and play and look around. As it was christmas there were a fair few visitors too, including a couple of toddlers, who weren't allowed anywhere near the cats but were very noisy (as kids are) and my cats are scared of kids as they rarely come across them. Towards the end of the stay they were more relaxed, but still very much preferred to hide and sleep unless it was quiet.
I did take the most laid back cat out into the garden on a lead and he enjoyed that, but the other two wouldn't have coped so I didn't try.
I'd say that if your parents house is likely to be calm and quiet then go for it. I'd take mine again rather than leave them with someone who would forget to feed them and let them in/out.