Lena lake is an easy hike, upper Lena is a tougher hike and will get you further from people.
After having a Margaret bull tag last year I sure learned to love that Margaret backcountry. Beautiful country and pretty easy walking, but you can really get up there and away from people. Some great fishing as well.
Mildred lakes is good. Staircase has some good hikes, but all those areas seem to get real crowded in my opinion. I went up to Ellinor two weeks ago and couldn't believe all the people, and it's early in the season.
I've also had some great hikes off chinook pass, it's an easy spot to access the pacific crest trail and get into the high country. Great trails and awesome scenery.