If I remember correctly Flying Dog trail, near Jeremy Ranch, has quacking aspens (must be similar, if not the same thing) and has plenty of distance. The best places to ride are the bike parks Deer Valley and the Canyons but they may be crowded. To get less crowded you can try heading up to the higher elevations around the Park City Epic (Wasatch Crest, Mid-Mountain). Over the summer I rode a new trail called Wasatch over Wasatch. It’s a fun 9 mile downhill from Guardsman’s Pass to Midway. I only saw one other rider. I know that’s technically not Park City but it’s all in the same general area. There’s a nice system above Midway too that may be worth checking out.