Originally Posted by
tsastor
Planning to visit the Taj Mahal from Delhi, preferably as a day trip. GUWonder suggested in another thread to take a guided tour.
Are there tours that utilize the fast trains from Delhi to Agra? Can you pre-book a tour that meets you at the Agra train station and drops you back so that you can still get to your hotel at Delhi for the night? Or are the return trains so bad (e.g. 10 hours late, see below), that it is better to hop on a tour bus from Delhi?
Can you book tours over the net? (I am a little afraid that booking a tour using a concierge at a 4-5 star hotel may be prohibitively expensive).
Finally, is there so much to see in Agra that it is better to stay there overnight?
A lot of questions, even though I have read these threads

There are tours that utilize the Express trains from Delhi to Agra, but more common are the bus tours that are day trips. The guided tours using the tour buses are usually cheaper.
The only thing that most foreign tourists to Delhi see when having the Taj Mahal on the itinerary are the Taj Mahal and Agra Fort. Some stop by Fathepur Sikri, a temporary, purpose-built capital of a Mughal emperor that was later abandoned and never really much fancied to begin with. Easily pulled off with just a day trip.
When I take visitors to Agra from Delhi, I usually schedule an overnight in an Agra hotel, just so there is some chance to see the Taj Mahal at night and avoid the road traffic back to and around Delhi in the evening.
Morning express train up and bus or hired car back to Delhi after very late dinner and lounging has worked for me before, but plenty of people get exhausted unnecessarily that way.