A.,
Check out the YMCA in Bothell off of Beardsley/195th (from 405). We have been members there for about a year and a half. Registration for the next session is about to begin the price is anywhere from $21 to $63 depending on if you're a facility member or not. The Y also has scholarships if, like us, you are a low income family.
I was just recently added as a swim instructor, so I'll be shadowing more experienced teachers and learning from them before I teach on my own.
Your older daughter would be either a polliwog or a pike (beginning levels), and your younger would be a pike as well. If you or your kids aren't keen on the idea of being in the water by themselves there is also a parent/pike class where you can get in the water with them.
As for instructors M. does the parent/pike class and she's awesome. She's the one that encouraged me to apply for teaching. Krystal and Amanda are also good instructors. My son (4 1/2) has had both and learned the most from both of them.
Because the Y is a full gym sometimes the locker room collects used towels all over the place, but the shower are clean, and warm. There are 5 open showers, then a whole bunch with curtains. Overall I'm pleased with the way everything looks there.
Hope this helps,
Melissa