SD is slightly more expensive than Seattle, especially once your two years in subsidized grad housing run out and you also factor in gas for having to drive everywhere and whatnot so the stipend difference shouldn't be a huge deal. The biggest difference I noticed with the grad students was at the poster sessions. At UW, all the students seemed to explain their stuff really well whereas at UCSD the grad students were like "well, what do you want to know?" One guy kept using acronyms and referring to "the currently accepted model" without bothering to explain wtf those were and when asked to clarify, just used more acronyms, hoho. I think UCSD was also the only school I visited where there wasn't a grad student seminar session, but maybe I'm remembering wrong??