- Ghiradelli square for an amazing sundae
- Pier 39- make sure you walk back behind the stores so your 4 year old can see all of the crazy sea lions
- California Academy of Science (it's a little pricey- I think $25 for adults, not sure of the kids price)
- Exploratorium is great!
- Golden Gate park has paddle boats that you can rent on Stow Lake, or bikes to rent (the silly ones the whole family rides on)
- Golden Gate park also has The Japanese Tea Garden which is fun...if your child is a girl. Boys might not think it's so neat. And they have The Children's Playground, which is just a huge playground if they need to get out some energy.
- Alcatraz is fun (but it might be better for a little bit older than 4). Beware of the wax Museum and Ripleys Believe it or not. They are funny, but I have taken 5 year olds in there when I worked for a summer camp and it was too scary for them.
-Ocean Beach is fun (not for swimming though...just enjoying the view)
- The zoo is pretty good.
- ride in a cable car (but be ready for a long line!)
As a 4 year old, my favorite things in SF were definitely the top four things on this list