Bring an umbrella- it does rain. We do use umbrellas, no matter what a guidebook tells you. Also rain boots are a pretty big staple.
ATM and Credit Cards are accepted most places. Chase is one of the major banks in Seattle.
Check out Redtricycle.com for weekly events and reviews on fun kid stuff to do
If you want to travel on the cheap, there are a multitude of parks to visit. Check out Things to Do In Seattle for all of the sights the kids and I are checking out in the area.
Buses- a bus trip will now cost you US$2.25 (check rates as they do change almost every year). You can get a transfer if you need to change buses to get to your location. You must use exact change when riding the bus. You can also buy a bus ticket book at drugs stores and other locations.
Taxis- don’t bother unless you are staying downtown. You won’t find them in too many neighborhoods.
Car- A car is almost a must if you want to explore outside of the city. Definitely budget in a rental car if possible.