Visitors to the Cascades in Central Oregon find the area pleasantly uncrowded, making it the perfect choice for a serene summer vacation. The city of Bend, Oregon is a good location for your base. From there, numereous hiking trails can be accessed. You'll take in amazing views of Mount Bachelor, The Three Sisters and Broken Top.
If you don't want an all-day trek, try the Tumalo Mountain Trail which is a relatively easy hike that finishes with awesome views of several peaks of the Cascades. There certainly are much more challenging hikes in the area, but this one isn't technical. The trailhead is off of Highway 46, about a 1/2 mile east of Mount Bachelor Ski Area on the north side of the road. To get fantastic views with even less effort, take the ski lift up Mount Bachelor. There is a restaurant up there too.
The only downside to hiking around here in the summer is dusty trails, and that's due to the volcanic pumice. Also, be sure to watch for fast-developing storms. You don't want to be above the treeline if lightning strikes.