Best time to visit nainital can be divide in 2 parts. One during May June when delhi becomes too hot you got nice pleasent weather here. Second during January February when heavy snow fall happens here. This review is based on 2 nights 3 days stay during last week of May. Best sight seeing local naini lake (mall road), Naina Devi temple (naini lake), cable car (mall road), cave garden ( 2 kms from mall road), Himalayan view point, snow point view, suicide point. Adventure park. By cab rs 1500 in peak season. Hotel stay during peak time will surely hit your pockets. Few good hotels of mall road: channi raja (rs 4500 to rs 8000) per nigh, mannu maharani (10k+) per night. These all spots you can covered in day 1 if you come reached early morning by ranikhet express to kathgodam from delhi. Tools nearly 9 hours and one and half hours journey by taxi to nainital don't pay more than 600 rs. Day 2: you can visit outer areas like woodland water fall, saritala lake, botanical garden, hanuman gadhi which will cost 2000 by taxi. (Naveen driver-9759274850 is nice you can contact him for better rates he explain everything good and nice behaviour. Overall roughly estimate approx. 35000/- per couple with single room stay of you come in peak season. Return journey you can plan by Satabdi express which took 6 hours to delhi. Hope my review helps you to plan your journey.