It depends of you're are going for trek or site seeing. For best trek go Chopta and do Chandrashila trek else Mussouri, Nainital, Rishikesh, munsiyari, auli you can visit.
Yeah. I am form Uttarakhand. You could visit Uttarkashi- Gangorti Road trip.Dayara Vigyan trekking, Tunganath , Valley of flowers. it's the peak time for all the Visitors. You could see this time the blooming Uttarakhand.