Need travel recs for Doon!

Hey there! I'll be travelling to Doon in February for a friend's marriage and I plan to visit the beautiful city as well. Obviously I've done my research but I've noticed that often enough what the internet suggests is mostly disappointing. Therefore, I'd like to ask the locals for the must visit places and hidden gems that are worth visiting. I'll be here for 9 days in total and I plan to roam around and experience the city and its neighbouring places (Mussoorie/ Rishikesh/ or whatever you guys recommend) for 5 days ideally. So please help out a fellow tourist please 😅