Also, when the weather improves . . . if you go straight out I-90 about 1.5 - 2 hrs you'll hit some good areas there. I can give you more info later but:
Easy: North Cle Elum trails
Several former mining roads that are deteriorating into some modest trails. They're easy but they also take you up into some beautiful territory in the heart of the Cascades on the eastern side of the range. Eventually top out at 6,000 ft of elevation with good views at the highest reaches. A favorite is the trail that heads up to Gallagher Head Lake (a small, pristine alpine lake ringed by rocky peaks). Fortune Creek Trail I think it's called. There are only about 3-4 trails up in this area. I think the trails open mid / late June once the snow is clear.
More Difficult / Mixed: Libertt / Table Mountain
Lots of trails surrounding this town on either side of Hwy 97 just north of Cle Elum. Plenty of camping. Steep trails. Not necessarily a lot of rocks and logs to climb over but any hint of moisture and the clay based trails get slick as snot.
More Difficult / Mixed: Manastash
South of Cle Elum and Ellensburg this is one of my favorite areas in the entire state. LOTS to see here with almost 100 miles of trails (vs. ~16-20 miles at Evan's Creek). The trails range over 115 sq miles of territory. There's some rock crawling, hidden lakes, rock gardens, steep climbs, surreal landscapes, beautiful meadows, ridge lines, you name it. The bonus is that you CAN get here via 4x4 trail that starts on the western side of the Cascades. Head out of Enumclaw along Hwy 410 toward the mountains, you'll pass through the town of Greenwater. Just past that town take a left on Forest Service Rd 70. it'll eventually lead you to the trail head to The Naches Trail.
Easy-ish: Naches Trail
I love the historic nature of this trail. It was an old wagon train route dating back to 1853 and the Longmire Wagon train. The trail was opened to Jeeps on its centennial in 1953 by a bunch of Jeepers in old WWII Jeeps. It's been run ever since. Near the actual pass is Government Meadows and the crossing of the Pacific Crest Trail (a hiking trail that stretches from the Canadian border to the Mexican border). This is where the pioneers camped for 2 days before lowering their wagons down cliff faces with oxen and ropes.