The Necklace Valley might be a good option, though I'd check the snow levels with the rangers first. This one's high on my list.
Also consider the Wild Sky and Henry M. Jackson location --
There's a loop hike there that's between 20 and 30 miles long IIRC, but I don't have the guide with me at work to look it up. It includes Benchmark Mountain in the loop, and a short stretch on the PCT. I can't bring the mind which trail it loops back on, but with a little bit of road walking (IIRC under 1 mile) it becomes a loop. And the area is gorgeous.
One of the rangers recommended the Seven Lakes Basin in the Olympics very highly.
I was going to suggest this one
http://www.wta.org/go-hiking/hikes/spider-gap but I think it's a bit too long for 3 days. (44 miles.) That's what you get for relying on memory when you're absent-minded... and thinking mostly about the views. :)
If you look at one of the Green Trails maps, you ought to be able to put together a loop hike in the Middle Fork Teanaway valley also, or take a gamble on the Enchantments... but for that one call the Wenatchee-Okanagon ranger station first, as it might still be too icy for a safe traverse. If it IS clear, and you can get passes, it's worth it. (If you do it, go in via Colchuck if possible; it's steeper than going in via Snow Lakes, but also 4 miles shorter -- same elevation gain...)
This one also comes highly recommended (by a couple of folks who know the area very well, since one of them has actually circumnavigated the Wild Sky Wilderness in order to validate and document its boundary -- he was one of the folks that helped to get it established)
IIRC it's a loop, beginning at the Quartz Creek Trailhead in the North Fork Skykomish River drainage, and culminating in a stunning vista from Bald Eagle Ridge, giving you a view of the entire Wild Sky Wilderness... this one's high on my list for this summer also.
I hope that helps :)