cargo carrier suggestions?

[sz9144]

my family and I are driving out to disney in august and we're thinking of investing in a roof top cargo carrier. we don't know whether to go hard sided, soft sided, how much cubic feet, etc. Basically I think it will end up holding small duffels, clothes, perhaps nonperishable food items. we would love one big enough to hold 2 umbrella strollers.

Thanks in advance!