berkeley is great because of LBNL. having access to equipment at the ALS and NCEM is an incredible opportunity. However, I feel like the MatSci department at berkeley is really small and so you don't get a lot of choices in professors you want to work for. but you're applying to AST so you're not limited to just searching in the MSE department.
IMO, Northwestern would be higher up on my list because they seem to have a lot more going on and a lot more support for their grad students. but i don't really know because i don't go there.
In terms of weather and food though, nothing beats Cal. I am deciding b/w northwestern, stanford, and am waiting on mit. i wouldn't know where to go until I visit.