Visiting Seattle

For just a weekend, I'd say definitely take a ferry, maybe out to Tilicum Village, if not for the show, for a stroll around and the boat ride is a nice short one. Any ferry you take to hike and picnic around any of the islands is a super fun day trip.
Pike's Place Market is a must, and touring the waterfront would be easy and fun. The sights, sounds and smells can't be beat.

Woodland Park zoo is wonderful, and The Discovery Museum is a lot of fun for little one's too!

http://www.wsdot.wa.gov/ferries/
http://www.pikeplacemarket.org/
http://www.zoo.org/
http://thechildrensmuseum.org/

- Space Needle
- The Freemont Troll under the bridge - ask for directions, it is very cool!
Here's a link: http://www.roadsideamerica.com/story/2236
- Pike Place Market
- Take a ferry to Whidbey Island - this place is beautiful! - only an hour away
Here's a link: http://www.whidbeycamanoislands.com/

There is so much to do in Seattle, you won't be bored!

I would recommend the children's museum. I'm not sure of the exact name, but the main one I think by Seattle center - it is really awesome! Plan to spend as much time there as possible! Pike's place is also super fun to see and alot of visual stimulation for a 17 month old. Have a great time.

It will depend on where you're staying. If you're in Seattle, downtown or close, then yes the waterfront, Seattle center, pike place market. Pacific place has awesome upscale shopping and restaurants, and the space needle's rotating restaurant is fun to experience, or just the observation deck, but for what it costs I'd just eat there! I'd you're staying by the airport, skip woodland park zoo or Seattle aquarium and go to point defiance zoo and aquarium in Tacoma, much better! It's about 45 minutes south of Seattle but only 20 from the airport. Ferry rides are fun, go to whidbey, camano, or poulsbo/bainbridge. Bremerton is a naval town, which can be fun too. My oldest would have loved the Fremont troll at 17 months, but my youngest would have been scared. The Ballard locks are cool, so is the Japanese garden at the arboretum. Madison park beach and alki beach are fun, and the childrens' museum at Seattle center. There is plenty to do, you'll have fun here!

I went there for a conference last year and loved it. I only had time to see Pike's place market but there is a place there that makes fresh donuts that melt in your mouth. Eat some for me please :)

The Children's Museum is great! Pike Place Market is fun too.