Well I donno what u wud be here for, I mean holidays or a tech-break

so I'd suggest the following, considering it to be the former idea:
1. Do NOT forget C.P. Be it a late evening stroll on a weekend or for shopping, this place rocks.
2. South Ex., combined with Khan Market area are also worth a visit.
3. Do visit old Delhi, be prepared for a lot of maddening rush, and keep ur wallet/cell/expensives safe. Try Paranthe Wali Gali, have some speciality stuff, and later a glass of lassi at Giani's. (I feel that after CP n South Ex, Old Delhi wud be a shock, but still a must!)
4. As u mentioned, Nehru place for tech junkies is a must visit.
5. If you can spare some time, u can visit a lot of other places near Delhi, including the NCR.
Others pls also contribute here.