Uttarakhand is very big city you first need to focus on which part you need to visit.if ur fond of lakes u can go to nainital 2-3 days are enough for it. if ur fond of views in mountains u can go to Missouri, dhanaulti,kanatal 3-4 days are enough. if u want to travel further more Auli is a place to visit but u must go in winter's to see auli at its best 4-5 days are must. if ur holy person try visit haridwar and Rishikesh 3-4 days are more than enough.