Though it's a short hike, Sourdough Ridge provides just the right amount of views and elevation gain, so the whole family will feel like they got a lot of views for just a little exercise.
From the visitor center parking area at 6400 feet, climb a set of large stairs through a wide, green valley for a little more than half a mile. This is Yakima Park, and you (along with many other hikers) are heading to the Sourdough Ridge trail just above you.
Some of your fellow hikers may be heading to Dege Peak, you'll know if they are when you reach a 'T' junction and they head right. Dege (pronounced Deh-gay) is a wonderful first summit for first-time hikers -- consider it as an add on to your ramble along Sourdough Ridge.
If Dege is not in your itinerary, peer over into Huckleberry Valley at the T intersection before turning left. This is the Sourdough Ridge trail. After a short but steep climb, pass under Antler Peak, and come out to views of Little Tahoma, Mount Rainier, and the expansive Sunrise valley below. It's 1.1 flat miles along a highline overlooking the Sunrise Valley to a five way intersection, where you have options for your hike.
At the five-way intersection, head left to Burroughs Mountain or turn right and climb to Fremont Lookout, both rather longer than the 2 miles of Sourdough Ridge. If you want a bit more, but nothing too steep, you could make a sharp left and loop back to Sunrise via Shadow Lake. Proceeding straight ahead will eventually take you to the Wonderland Trail, Skyscraper Pass, or Berkeley Park, all of which are considerably farther away. Turning right around, your final option is to retrace your steps, and perhaps venture to Dege Peak, before returning to the trailhead.
No matter your route, the views will be stunning -- Sunrise offers some of the best views available at Mount Rainier National Park. Just be prepared if you select a longer route.