This is a nice 2000x200 grass strip located west of Portland, OR. The only operations here are the Willamette Valley Soaring Club (www.wvsc.org). They have an active club and own lots of gliders and tow planes. This field has been in use since about 1968. I got a chance to do some flying here in June and July 2006. I had a great time and had the opportunity to take some of my family flying.
The typical flight from North Plains is a tough number to come up with. Many training flights only last about 30 minutes, the time it takes the glider to return to the airport. That said, experienced members flying out of North Plains frequently catch thermals and fly for two to three hours. We don't have the consistent conditions like you would find in places like Reno or Ephrata. The good news is it is close to Portland which makes it a great location for lots of people to fly.
We normally tow to 3000, which makes a 18-20 minute ride if there is no lift. If there is good lift, you can stay up for hours. Both Ginny and I have done the "big sit", a five hour flight.
John