It's hard to tell how a nonpartisan commission will draw maps. As we've seen with Iowa's first round of maps, they can make some unusual choices. For this map, I tried to hew as closely to the existing districts as possible, within reason; there are some odd territorial splits (such as WA-09 jumping across Puget Sound) that might make more sense to a local than to a East Coast resident like myself.
I tried to limit city and county splits where possible, but sometimes it was unavoidable. The biggest split is Tacoma, half of which I had to put in WA-06 and half in WA-09. I also tried to either ignore partisan data or encourage competitive districts. Thanks to the way the map is set up currently, the latter was pretty easy to accomplish; there are five districts that I would consider competitive (WA-02, 06, 08, 09, and 10).
WA-01 (blue) - Instead of jumping across Puget Sound, it stretches across northern King County and farther up into Smohomish. Old district: 56.2% Murray, new district: 56.5% Murray.
WA-02 (green) - Expands very slightly, picking up a little bit of Snohomish and dropping the one random descent into eastern King County. Old district: 50.5% Murray, new district: exactly 50.0% for each (the margin is 118 votes in favor of Rossi).
WA-03 (purple) - This one probably changes the most. Northern end of the district is chopped off, and it moves east to Yakima. Old district: 52.5% Rossi, new district: 55.5% Rossi.
WA-04 (red) - Moves east, losing Yakima and gaining Walla Walla. Old district: 64.4% Rossi, new district: 63.9% Rossi.
WA-05 (yellow) - Loses Walla Walla, gains bits of Franklin County. Old district: 58.6% Rossi, new district: 58.4% Rossi.
WA-06 (teal) - Drops part of Tacoma, picks up islandy parts on the west side of Puget Sound. Old district: 53.1% Murray, new district: 53.0% Murray.
WA-07 (grey) - Seattle and a bit of the suburbs south of it. Old district: 81.0% Murray, new district: 81.5% Murray.
WA-08 (light purple) - Loses Pierce County. Adds a bit of the inner Seattle-area suburbs. Old district: 50.8% Rossi, new district: 53.0% Murray.
WA-09 (sky blue) - Loses the southwestern swath of territory, picks up a bit on the northern and eastern borders. Old district: 52.8% Murray, new district: 54.1% Murray.
WA-10 (magenta) - The new seat. Most of Pierce County, all of Thurston County, and some parts south and southwest of Thurston. 50.9% Rossi.
I don't know if anyone got drawn out of their districts, but the only incumbent that would probably be seriously miffed is Reichert. Losing Pierce County would be a blow to his re-election chances. He could always move to the new WA-10, though.