Any tips for living cheaply in SF?
thesethings: Regarding the weather, I've lived in both places, San Francisco is much colder in the summer than Seattle.  San Francisco, and most of coastal Northern California, barely has seasons. 
Though Silicon Valley and the East Bay (Oakland, San Jose, etc) do get warmer, San Francisco, being surrounded by water on 3 sides, just doesn't get hot in the summer  beyond a random handful of days. (On the the other hand, it also barely has winter :D)
Bring your jacket(s)!