Boots for Mt Shuksan!

You might consider going to http/cascadeclimbers.com and asking there. They are Pacific Northwest climbers.

Which rout would be of significance.

But you will probably find that all of the locals will be in single fabric-leather boots. La Sportiva Trango's and Scarpa Triolet's are in pretty much every gear shop in this state, and especially in august that's what just about everyone has on.

I will be climbing Mt. Shuksan via the Sulphide Glacier rout.

-Joseph

I don't think that rout will be terribly demanding on the footwear. It will be critical that your boots fit well first and foremost, and you'd like them to shed water well, since you will probably be slogging through some slush up high. You don't want a fully rigid boot, as you will do quite a bit of hiking along the way.

In some ways it depends on what else you want to do. Fabric boots like La Sportiva Trango's, in whichever make fits your feet best, will be the lightest option. If they are newish they will be fairly waterproof, and with a good sock system should keep your feet warm enough. These sort of boots really shine most on steep rock, so if you do much scrambling or alpine rock as well they are the way to go.

For a little more water-resistance and warmth a full-leather boot with a not-rigid sole and a crampon groove in the heel would be fine. More durable and heavier. Might be a good choice if serious off-trail backpacking is also your game. Scarpa SL M3, La Sportiva Glacier, etc.

Rigid-soled boots intended for ice-climbing could work, but you'll hate them on the approach. Plastics you would hate even more on the approach. If you were going to use either of those you would probably want to carry them for the approach and hike in some light shoes. That could be a good option if you happen to own some boots like that and don't want to buy another pair.

Note: Perhaps I should mention that if you have particularly poor circulation, or possibly previous frostbite injuries, than the approach shoe/double boot combination might actually be the best choice.

Go with the lightest new-matic crampon boots that fit well.

Look at the Garmont Tower or Vetta Plus. They work well on the approach and on glacier/snow/rock.