The Central Cascades...
is the area I have probably spent the most time in, which is easy today as this is probably the largest area for adventure in our beautiful Washington State. I consider the central cascades to start south of Highway 2 and end North of Highway 12. This area encompasses so many different wildernesses including the Wild Sky Wilderness, Henry M Jackson Wilderness, Norse Peak and Clearwater Wilderness, Willam O Douglas, Glacier View, and Tattoosh Wilderness, along with my personal favorite, the Alpine Lakes Wilderness, and of course, Mount Rainier Wilderness and National Park. Mount Rainier which is known natively as Tahoma "Mother of Waters" is the tallest mountain in the cascade range and is an active volcano, last erupting approximately 1000 years ago. From beautiful waterfalls to alpine lakes and summer wildflowers to the larches of autumn, the central cascades has endless beauty that really would take a lifetime to explore in its entirety.
For first time visitors, I would of course recommend visiting Mount Rainier National Park, the link below to the National Park Service website has great resources. In regards to specific trails, Panorama Point and Golden Gate out of Paradis and Fremont Lookout out of Sunrise is a classic as well as Comet Falls and Spray Park. All are beautiful ones but are often busy in peak season. Outside the park, there are so many trails and my best advice would be to check out the Washington Trails Association link at the bottom of the page and find the hike that's best for you and what you want to see. The options are endless really.
FUN FACT: Mount Rainier is home to 25 glaciers and source to 9 major rivers, hence the native name Tahoma, given by the Puyallup tribe.
Explore the Central Cascades:
Below are just general resources to help you find your next adventure. This is really just the tip of the iceberg but I hope it helps. If you are looking for backpacking info search for the Backcountry Wilderness Map on the NPS website.