Do you know if her kid is mobile yet? If so, I recommend doing things in outdoor spaces... parks, etc... at that age, it can be fun to just let them loose in places like that and follow them around.
If the kid is not mobile yet, going places that are specifically kid-fun probably isn't as important yet. Take them anywhere that there are interesting things to look at.
The kid might be a little young to really get the Exploratorium, but I think it's pretty fun to go to as an adult and there are certainly lots of buttons to push/levels to pull/etc even if the kid doesn't understand what's going on.
Carousels may be a hit with the kid-- some 1 year olds really love riding them (with adult accompaniment), I guess because of the lights/colors/music. There's one in Golden Gate Park which is supposed to be nice, and one at the Zeum kids museum, and probably more around to boot.
"Hummus; a gentleman's vice." -- Mars