I have just returned from Hunza-Nagar and Ghizar visit. (April 4 to April 9)
Hunza was in full bloom. I stayed in Hunza View Hotel (Rs 1,500 for a spacious room with two master beds and free extra mattress).
Boats are available at Attabad lake.
Don't waste your time on Naltar valley. Nothing there in April.
Yes, visit Nagar Khas but no spring in Hoper village.My visit there was not a waste as I enjoyed visiting Hoper Glacier.
Gupis is in full bloom. I enjoyed the view of Khalti lake. I stayed at PTDC Motel (Rs 3,000 per night, but there was an economical hotel some 2 kms before Khalti lake. Demanded Rs 600 for a room with three beds and extra mattress was not a problem). Yaseen valley visit was just 'so so'.
In Phandar valley no spring at all. so don't think of going there.
Now I am in Skardu. You have missed Skardu spring as there are very few flowers left on trees.