leora's info on Hood is accurate.
Dorr Fumaroles are at base of the Cockscomb on Baker - seldom visited.. The most direct route to the Sherman Crater on Baker is via the Squak glacier (fewer other climbers en route, as well).
there are lots of fumaroles around the rim of both craters on Rainier, but active sulphurous venting locations seem to change from year-to-year. I've noted them with regularity on the northeast-to-east segment of the "new" crater rim, downslope from Columbia Crest, and on the west rim of the "old" crater. I've not explored down to the Grotto yet. That would be fascinating.
also felt rocks too hot to touch with a bare hand along the spine of Disappointment Cleaver, with brief scent of sulphur when the wind wasn't howling it away.
smelled sulphur on summit of Adams when the wind was blowing from the east toward the cabin, but did not investigate the source. also have photos of fresh-cooked sulfur in the saddle at the head of the Adams Glacier (you'd need to go in August of a low-snow year to see those deposits).