Here are some of the event and supported rides in the area. Never to early to plan! (Actually it maybe. One event does not have its date finalized.) Of course, the list is not all inclusive, but it does represent well over 3000 miles of riding. The multi-day rides include the assembly day at the start, except for the STP.
Monster Cookie ride (Salem-Champoeg loop) Sunday, 4/26 http://www.salembicycleclub.org/content.plx?page=majrides
Ride around Clark County--RACC (Vancouver, WA loop) Saturday, 5/2 http://www.vbc-usa.com/racc/
Reach the Beach (Portland or Newburg or Amity or Grand Ronde to Pacific City one way) Saturday 5/16 http://www.reachthebeach.org
Ride for Two Rivers (Sisters to McKenzie Pass out and back) Saturday 6/6 http://sisterscountry.com/Ride-For-Two-Rivers
Pioneer Century (Canby loop) Saturday 6/6 http://pwtc.com/pioneer
Strawberry Century (Lebanon loop) Saturday, 6/13 http://www.santiamspokes.org/Strawberry%20Century.htm
Gorge Ride (The Dalles to Mark O. Hatfield Trailhead near Hood River out and back) Saturday, 6/20 http://www.hcrh.org/2015-gorge-ride/
Petal Pedal (Oregon Gardens, Silverton loop) Saturday 6/27 https://www.athletepath.com/petal-pedal/2015-06-27
Mt Adams Country Bike Tour (Trout Lake, WA loop) Saturday 6/27 http://troutlakewashington.com/mt-adams-bicycle-tour/
Cycle Oregon Weekend (Monmouth 2 days, loops) Friday 7/10-Sunday 7/12 http://www.cycleoregon.com (Sorry, my need for symmetry forced me to include this link)
Tour Des Chutes (Bend loop) Saturday July 11 http://tourdeschutes.org/
Seattle to Portland (STP) (Seattle, WA to Portland one way) Saturday 7/11-Sunday 7/12 http://www.cascade.org/node/6801
Oregon Bicycle Ride (Roseburg-Coquille-Bandon-Gold Beach-Merlin-Azalea-Myrtle Creek-Roseburg loop) Saturday 7/25-Saturday 8/1 http://www.bicycleridesnw.org/2015/2015-rides/oregon-ride/
Portland Century (Portland loop) Saturday 8/1 http://portlandcentury.com/
Providence Bridge Pedal (Portland loop) Sunday 8/9 http://blog.bridgepedal.com/
Covered Bridge Bicycle Tour (Albany loop) ???was Sunday August 10, 2014??? http://www.mvbc.com/event-CBBT.html
Idaho Bicycle Ride (Blackfoot, ID-Ririe, ID-Hoback Junction, WY-Henry, ID-Lava Hot Springs, ID-Blackfoot, ID) Saturday 8/8- Saturday 8/15 http://www.bicycleridesnw.org/2015/2015-rides/idaho-ride/
Ride Idaho (Coeur d’Alene, ID-Kellogg, ID-Wallace, ID-Noxon, MT-Troy, MT-Sandpoint, ID-Coeur d'Alene, ID) Saturday 8/15-Saturday 8/22 http://www.rideidaho.org/
Cycle Greater Yellowstone (Red Lodge, MT-Absarokee, MT-Red Lodge, MT-Cooke City, MT-Cody, WY-Powell, WY-Red Lodge, MT) Saturday 8/15-Saturday 8/22 http://www.cyclegreateryellowstone.com/ (If you are worried about Day 4, do Day 3 of this tour to prepare.)
Crater Lake Rim Tour (Diamond Lake to Crater Lake Rim Road loop and back) Saturday 8/29 http://www.mvbc.com/event-CLRT.html
Tour de Blast (Toutle, WA) Saturday 9/12 http://tourdeblast.com/
Cycle Oregon Week Ride (Baker City--- Oh, wait. Just click the link above) Saturday 9/12-Saturday 9/19 http://www.cycleoregon.com
Peach of a Century (Salem loop) Sunday 9/13 http://www.salembicycleclub.org/content.plx?page=majrides
Harvest Century (Hillsboro loop) Sunday 9/27 http://harvestcentury.org/