Standing in front of the ice cave (not as close as you think), I got blasted by a cool mist. It is not a good idea to walk into the caves because bits of the roof fall off like the chunk pretty close to me.
We almost camped at Gold Basin Campground with some Aussie friends, but the weather was pretty dreary and the hardy camp manager cheerily suggested bucketloads of rain were on the way starting from midnight and that we might need a tarp and to dig a few channels for the water. It explained why the whole area was so lush and green. Instead we decided to stay there for the day and do the Ice Caves hike before heading home.
The campground is well organized and this means you need to book at least 3 days in advance to camp (perhaps this is also due to the weather and the number of no-shows we saw at the camp). Unlike many Aussie campgrounds, each site here was well-separated from the rest and many were partially surrounded by dense forest which was impressive when walking around the site.
The Stillaguamish River flows near the campsites.
As we were driving to the Big Four walk we saw several other campsites, some of which were official and some were just folks camping beside a river, so the whole area looks like it would be worth going back to check out again. I'm sure there are also other decent hikes to do in the area.