Delhi is a huge, sprawling city. It's best to choose a hotel near the area where you will be doing the most.

Quad rooms are not common in India. You may have to get two double rooms.

Everyone has a different opinion about how much time to spend in Delhi. It might be good to start your trip with Delhi so you can recover from your flight. Probably two days (not including your arrival day) would be plenty.

Tourist attractions are best seen in the morning before they get crowded. Use the Metro when possible to avoid the gridlock Delhi traffic (worse during morning and evening rush hours).

we stayed at the hyatt and it was very nice... they must have a pool but i don't remember it..

another time we stayed at the nikko metropolitian and it has a nice out door pool

The Maidens is a good choice if you are planning to see sights near old Delhi. Another decent option is the Claridges on Aurangzeb Road. They both have decent swimming pools but without a specific budget range its difficult to guess what would be good value for money.

Thank you so much for the information of the specific hotels rhkkmk and galactus. I have been surprised at the expense of staying in Delhi. Since it appears there are not many 4 person rooms, this means that we have to get 2, so the cost adds up quickly!
Jaya, thanks for the advice about the amount of time to devote to Delhi. We decided to fly straight to Varanasi first since we are at the airport anyway, so will be staying in Delhi at the end of the trip for the last 2 days . We accidentally made the arrangements for 3 AM(!) departure from New Delhi,on 1/3/13 ,so not quite sure what to do .We have heard from other blog posters that one can't get in to the airport until a couple of hours prior to the flight.Do you have any information? Any ideas about how to spend the time? Really appreciate the input!
Evelyn

I've had to wait til approx 9:30 in the evening to get into the Delhi airport to catch a 1am flight back to the US. Security seems much tighter than here in the States and they will check your id,ticket,etc prior to you even stepping into the airport. I do remember long lines thru security so you do have to allow an hour (sometimes longer) to get thru security. I don't have any input on how to spend the time but we were waiting in a building right across the street from the airport before we could go into the airport. It was crowded with I believe a concession area for food/drink. Inside the airport, once you have (finally) gone thru security, it is the same scenario of food/drink stands. Not sure if there was much else. Seems like a lot of the international flights take off after midnight. Boarding the plane is another security situation where they go thru your bags, etc 2 times at 2 different stations. Seems to be pretty throrugh so boarding also takes up quite some time (40 min or so?) It is a tiring experience at that time of morning.