Considering you've got only 4 days, you won't want to spend a lot of time on the way. Starting from Ghaziabad, you can visit the Kumaon region in the Uttarakhand as it offers a variety of off-beat locations.
If you haven't been to Mukteshwar, that would be a perfect pick for you. Located at a slightly higher altitude as compared to Nainital, Mukteshwar is known for its tranquil and calm environment.
There's a Mukteshwar Mahadev temple on the top of the hill where you can sit in the silence surrounded by the deodar trees and it follows a small hike through the forest and offers you mesmerizing views of Himalayan peaks of Trishul, Nanda Devi and Panchachuli (considered by almost everyone to be one of the best in Uttarakhand)
Brownie points - on your way to the view point, there's 1 small cafe (you won't miss it) that offers amazing momos. You can stay at Hotel Golden Peak (ask for the room with the balcony - it offers a great view of the sunrise) and its economical as well. Let me know if this was helpful and also let me know where did you visit.
There are two things 😀 I already visited Mukteshwar in 2019 and second is, Shivank said absolutely right about the weather conditions. In 2019 i went there in month of September & that was too rainy and landslide weather. even i saw land slide at three places in my way. and the huge rain will not
I too went out from Ghaziabad but destination was Chaukhutia Uttarakhand, do consider it...its a small village but it's an overwhelmingly beautiful experience with locals unlike the stereotypical hotel stays