I visited Nainital last year. I took a train from New Delhi railway station for Kathgodam. I reached in night so I waited till morning. In the morning around 5 am, I got help from a small delivery truck driver. He asked me to sit in his truck and pay 100 bucks. I really enjoyed the hilly ride, greenish big mountains and lovely weather throughout the journey.
The truck left me near the Nainital lake. I took a cigerate and a tea started roaming around the lake. My family was already there in Railway Holiday homes. I went there met them and then again went on discovering new places.
The local sightseeing is easiest, you book a cab for one whole day and it will take you to all the various sights in just around ₹; 1000.
Hotels are also easily available. Even OYO has its significant presence here.
Out of all the places I visited in Nainital, the best part was Governor's House, Naini lake and the Mall road.
Foods that I tried were simply momos, chats, ice Cream etc. Domino's is there on the mall road itself.
I stayed for 6 days, skated on mall road, enjoyed especially the weather. I would like to spend some more time there in Nainital because of it's peaceful and lavishly green environment.
I will recommend you this place for this summer. Stop living in Air condition and enjoy the real nature.