Laura, I am not too far away from where you'll be staying either (though at the opposite end from Aida. Edmonds isn't hard for me to get to, and like Aida said, the waterfront area is quite nice. Let me know if you would like to meet while you're here.
Commuting is possible through Community Transit from Edmonds, though I'm not sure the frequency of buses through the area you'd be staying at.
Here's the link if you want to try it. http://www.commtrans.org
Google Maps does provide some bus trip planning help through Community Transit, as well as King County and greater sound public transit (Metro, Sound Transit, etc. which are other agencies.)
The ferries are pretty large boats (holding hundreds of cars) and the crossing from Mukilteo to Whidbey Island is usually very smooth, as it's not out in open ocean. Whidbey is nice, and if you do rent a car, you could always drive farther up on the very, very long island (Coupeville is nice, which is where Fort Casey that Aida mentioned is.)
From Edmonds, you can also take a quick (30 min.) ferry, again on a smooth crossing and a large boat, directly to Kingston to reach the Olympic Peninsula if you want to explore some less suburban scenery. Port Townsend is about an hour's drive once you reach Kingston, and it's quite fun - Fort Worden State Park is very similar to Fort Casey on Whidbey Island, and downtown Port Townsend has a lot of cute local shops to explore.