Connaught Place, hands down! And the best thing to do here is to enjoy India's fuel - Chai! Here are a couple of Chai hangouts in the area:

1. Tea Trails Bistro 

This bistro has a very pleasant vibe, with its white ‘teapot and cup’ themed walls and vertical garden. It’s a great space to work, have an official meeting, or even for a date. There’s always indie folk music playing which makes it a nice, quiet place for good conversations.

Needless to say, they have an extensive tea menu. There are the classic kullad chais, the light English teas, and Asian teas which are fermented rice based as well as the more exotic infused teas like Red Zen. Tea is served in glass infusers and a sand timer to measure brew time which adds to the fun of the tea drinking experience. The highlight of this place is definitely its teas and the ambience which is perfect to relax and unwind. The staff is also super friendly and always happy to make a recommendation so don’t hesitate to ask questions.

Highlights: Soothing Ambience, Extensive Tea Menu
Must-Haves: Lemon Mint Iced Tea, Lychee Bubble Tea, Eggs Kejriwal, Chicken Curry 
Cost For Two: Rs. 600
Cuisine: Cafe

2. Wagh Bakri Tea Lounge 

This place welcomes you with aromatic wafts of cardamom the minute you enter. It’s nice to see this old brand of tea re-invent itself as a chic café. The décor is interesting with a tea cup chandelier, colorfully hand painted teapots, and framed posters of tea trivia and history; interesting to read as you wait for your cuppa.

An interesting element in their menu is the cold teas served with ice cream to suit a variety of tastes; kesar and pista as well as vanilla and chocolate. This place is nice for friends and families to come and spend quality time together and as one of the posters reads, “No WiFi. Talk to each other!”

Highlights: Decor, Cold teas served with Ice Cream
Must-Haves: Wagh Bakri Tea, Kesar Pista Ice Cream Tea, Banana Walnut Cake
Cost For Two: Rs. 700
Cuisine: Cafe
ju

This is just the tip of the iceberg.

Hi,

You can go these unique places in Delhi 

Parthasarathy Rocks

Rose Cafe

Indian Mountaineering Foundation

The Potbelly Café Chanakyapuri

Tonino

Sky Lounge Bar & Grill

Ice Lounge

Cafe Lota

Blue Frog Restaurant & Bar

I would do Safdarjung Tomb then walk down to Lodhi Gardens and based on budget pick either Khan Market or  New Madras Hotel..

If this meets your interests, i can share more monument like round trips for you.  

Lotus Temple if the best place for visit in Delhi

How about not going to a 'particular' place but just taking a walk down the streets of the city and sampling some food the city has to offer. If you are passionate about photography, you could also try your hand at clicking some great portraits or just busy street scenes. That would make for some wonderful memories. Also, Delhi packs in a lot for the foodies out there.

I did the same and it was all worth the experience. I came up with my own Delhi food guide. May be by the end of it all, you could come up with your own foodie guide too!

The possibilities are really endless, so just follow your heart and go. All the best!

Try

1. Kingdom of Dreams

Akshardham Temple

Lodhi Gardens

Diggin

India Habitat Centre

Hauz Khas Village, Deer Park

Khan Market

Delhiis so big and busy city. There are so many historical places to visit along with good restaurants and amusement parks are there.

Lodhi Gardens, old Delhi's street food, Nizamuddin, Vasant Kunj, My Bar Connaught Place and Cyber Hub Social

Akshardham

Hi! Arvind´s reply is great! I would add Purana Qila, Humayun's Tomb and Dargah Hazrat Nizamuddin which is all close by. If you decide to do so, try to attend the Qawali (Sufi music) of the Dargah. I am sure they sing on Thursdays evenings (both at 5 or 6 and at 9pm) but I am not sure about weekend timings. 

Should you be intersted, I have other ideas for Old Delhi.

On the other hand, there are plenty of heritage walks around Delhi, most of them are posted on Facebook. If you need help, I manage a Fb group where I post all the cultural events that are happening in Delhi. You might like to check it out. It's called 'Delhi - to do list': https://www.facebook.com/groups/Delhitodolist/ Enjoy!