Hwy 2 can get busy in some places, but overall is a fine and doable route, IMO. Hwy 20 is more dramatic and the Methow Valley of Winthrop/Mazamma beautiful, but Hwy 2 along the Columbia River from Coulee City to Wenatchee, then west to Leavenworth is beautiful as well. And Stevens Pass on Hwy 2 is only 4,000 feet, as opposed to 5,000 feet on Hwy 20 through North Cascades National Park. The west side of the pass on Hwy 2 is much more busy, so ride carefully. You're also socked into the tall pines on the west side, so it's less scenic. But you can veer off of Hwy 2 in Sultan and veer southwest towards Seattle or northwest towards Everett and Mukilteo to catch the ferry to Whidbey Island and then Port Townsend and the Olympic Peninsula.