I haven't been to Highlands in probably 15 years, I've been to Boyne Mountain maybe 6 days in the last 2 seasons though. I don't recall much in the way of off-piste or gladed terrain. Nubs has more, IIRC. (Crystal Mountain which is about 2hrs West has probably the most *dedicated* gladed terrain, none of it is really "off-piste" since it's between groomed trails and within resort boundary, but it's still kinda nice if not all that steep)
Remember that in the midwest we are dealing with much smaller acreage and a lot more private land so although it may be appealing to look over the resort boundary, that practice is severely frowned upon here and also FWIW there just isn't really the type of terrain you might be thinking of finding in Utah or CO sidecountry.