I attempted the Mt. Helen - Dyer traverse last week and loved it. We made it about 2/3 of the way, pretty much through the fun stuff, and then bailed out into Mohawk Lake basin because we did not like the look of the weather. But it is a really fun traverse that rarely gets traffic.
Kelso Ridge is great too in that it presents 3 really good class 3/4 walls on the way up. I also like Quandary's West Ridge, but the real fun stuff does not hit you until you are within 100 yds or so of the summit. It is a long walk down if you find out you are not up for the white rock knob or class 3/4 chimney that follows. Kelso gives you earlier warning signs, which is helpful if it's your first class 3.
Democrat's N. ridge is good too, but it is decent walk (about 4 miles) from the Montgomery Resevoir TH to gain the ridge. Beyond the Shark Fin tower and the big black slab that follows, you are mostly ridge scrambling to the summit. You can sweeten the fun by traversing to Mt Lincoln and descending via its amphitheater directly down to Montgomery, but be sure to get some good beta on the descent, because safe routefinding there is a challenge.
I need more dehydrogenase.