Hi Nick, You won't find much information about these people after 1930 because that is the most recent Census available to the public at this time. The 1940 Census will be released in 2012 but who knows how long it will take to get it indexed.
The Clark County Genealogical Society, www.ccgs-wa.org/ , might have scrapbooks or the County Directories which could tell you more.
You can look them up in the Washington State Digital Archives, to see if any of the children have died recently. After you find their death dates, contact the Washington State Library, www.secstate.wa.gov/library/ask.aspx to request a copy of their obituaries.
After I receive the obituary, I look up the survivors in www.whitepages.com or www.zabasearch.com to find current contact info.
That's the best way to try to contact descendants that I know of. Successful SEarching!