This is an old favorite with a new trailhead. Amy and I used to make this hike before it got all popular back in the day. The 360 degree view from the top of Mount Catherine is amazing considering the short roundtrip and the easy climb.
Casey and I did this on just to stay in shape. Its just perfect for Casey - only 2.25 miles from the trailhead to the summit and only 1200 feet elevation gain. The rocky summit is surrounded by 80 foot drop-offs so if you are taking small kids or animals beware of that particular danger.
On this particular day, the top of the mountain was infested by a cloud of flying ants. They almost chased me clean off a cliff!
If you go, be sure you have your Northwest Forest Pass. Here are the driving directions from the Washington Trails Association.