If I'm doing a topping on a dessert...I want real whipped cream. However, often times mixed into something else, Cool Whip holds up better.
I've been making a trifle-like dessert this summer. The recipe might be in here somewhere, if not and you want it, let me know and I'll write it up as I kind of made it up from a couple of others. Using CW just holds together better, as it has to set for 8-12 hours before cutting into and we've kept it for 5 days and it's still the same.
I also use it in a frozen dessert that's really good if you like mint, even though it sounds weird. I've had it for over 30 years and everytime I've made it, people really like it. When the kids were little, it was always the "salad" for Christmas dinner.