pretty sure (but call them and ask to be sure) you can use the spa services even if you're staying off-site. you just have to make appointments for the services like manicures/pedicures, massages, etc.
Riding at Crystal is varied, it is smaller than the Boyne resorts by about 100ft vertical, they have moguls, a decent gladed section, some steep runs, some wide-open groomers, they even have two small "bowls" which of course pale in comparison to anything West of the Mississippi but are kind of neat even if they're only 5-second rides down at full-speed. They added a boarder-cross course this season accessible from the North Face chairlift. You will never see lifties more enthusiastic about their jobs as the guys who work the Clipper high speed quad chair in front of the lodge.
more of a family-friendly atmosphere there and pretty laid back for the most part. The "park" area is really lacking since they removed the jumps back in 2007/08 season. The Thistle pub & grille has great food, not outrageously pricey for a resort, there's another restaurant on-site Wild Tomato I think which is decent, the rest of it is just meh cafeteria food. The bar there is nice. There is a gas station/convenience store about a mile down the road that has superb pizza.
I've been riding there for about 15 years even though there are better "mountains" in MI it's where my folks used to take us on vacation so it's always been kind of like a "home mountain" for me and I keep going back because it's familiar and they do a good job keeping it updated, developed, etc.
They should start paying me for these endorsements