We are planning to a four day trip to Delhi, India. TajMahal is on the list. What would be the other places we should consider?

None. Do an overnight in Agra (where the Taj is located) if you can. The Taj can be done in a day, I suppose but it is better to savor it and maybe enjoy some of the other sites nearby such as Agra Fort and the "Baby Taj". Also, the abandoned city of Fatephur Sikri is 45 minutes from Agra and is worth a couple of hours. In Delhi, there is plenty to see - two days worth plus time for shopping.

I agree with Craig that you should overnight in Agra, so that you can see the Taj at sunset and sunrise. the change in the color of the marble is really worth seeing. In addition to Fatehpur Sikri, the Bharatpur Bird Park is quite close to Agra.

I didn't especially take to Delhi, but there are a number of sights - the Raj Ghat and Ghandi Museum, the Baha'i Temple, the Red Fort, Humayan's tomb, the Qutr Minab, the Jama Masjid, Connaught Place, India Gate... Take time to visit the suburbs to see how the middle class lives, and note the shanty towns you'll pass on the way.

While planning, keep in mind that the Taj Mahal is closed on Fridays.

Good pointer by Jaya - since you have only 4 days - you need to be sure you are not in Agra on Friday when Taj is closed.

Also since you have limited time - it is best to restrict the number of places you visit - as each destination is a delight and it takes time to absorb the highlights.

Since you shall be based in Delhi - a good day excursion is Agra - but it is best to stay overnight and see Taj during Sunrise and sunset - when it is at its best - in multi color splendour as the sun rises and sets.

Jaipur is kind of far away for a day excursion - best to do it as an overnight tour as there sooo much to see there...

All the best

I think the most you can do is Delhi with a side trip to Agra. Delhi alone has plenty to do - ESPECIALLY if you are going to be shopping also!

You can get to Agra on the Shatabdi Express train. It leaves Delhi at 6am and you'll be in Agra by 8am. Depending on the return times, you could return back to Delhi by evening.

Don't drive to Agra - too much time wasted.

Also in Delhi, visit Akshardam Mandir (temple) - it's beautiful.