We are heading to Northern India in December and whilst we have the general itinerary settled we still have a bit of flexibility. So I thought I would come here and ask if others have any advice.

We are focusing on the 'Golden Triangle' so not heading too far off piste. Below is a list of the WHS and tlist sites in the area that we have contemplated, am I missing anything obvious is there a Tlist site nearby I haven't picked up yet?

Delhi: 3 WHS + 5 tlist? (in declining level of potential visit; Grand Trunk Road, Delhi: a Heritage City, Baha'i Temple, Silk Road, Saytagrah sites)
Agra: 2 WHS + 2 WHS nearby + 0 tlist?
Jaipur: 2 WHS + 1 tlist (Jaipur City)

Additionally how long would people recommend for the specific stages, how long to devote to Delhi for example?

Does anyone have any accommodation recommendations, or a general decent area to stay in Delhi?

For Delhi, I'd recommend 2 days to cover the 3 WHS plus one or two TWHS. I'd also visit the (Bahai) Lotus Temple (I vaguely remember visiting it in the evening?).

It takes time to get anywhere in the city, so probably the most important decision is which transport to use. I took the hop-on hop-off bus which gets you anywhere interesting, but takes ages ( http://hohodelhi.com/sightseeing-2/ ).

If you have enough time, the area close to India Gate would be great for accomodation/dining/walking and visiting WHS or tWHS. Otherwise use the airport hotels if you're in a hurry. They are a godsend for avoiding Delhi's terrible traffic before any flight.

I would highly recommend using a taxi (or a driver for a day + tuktuk the other day). That way you'll be able to cover more ground at your own leisure.
I'd also recommend visiting the Bahai Lotus Temple from outside (nothing really special inside) and also Akshardham.

Thanks for those responses, I hadn't even looked the other-side of the river, so good to know there is something out that way. I was just coming back to ask a further question:

- Is there anywhere else in the area that you would add on to that basic itinerary? (perhaps with two days to play with)

If I were you, with those extra two days I'd plan my stops carefully to take it easy where it's worth it and have more time to visit when there are less people (early morning or late evening or towards lunchtime). Most of the WHS in your itinerary will require quite some time to get there, buy tickets, visit interior and exterior, etc. and there are non-WHS or tentatives which you might as well visit while you're there.

Another tip would be to spend a bit more on hotels if you can afford it. The last thing you'll want after a long day is a lousy hotel experience or stomach problems because of the food served at your hotel. Heritage hotels and some boutique hotels will be a worthwhile investment.

During my unforgettable 28 day visit in India I focused mainly on Rajasthan but had enough time to explore several places from the Thar Desert (west) to the Ganges (east) visiting 11 WHS and 4 tWHS.
In October-November I'll explore the central and southern areas around Mumbai, Goa and Bhopal hopefully visiting 9 WHS.

I might have thought that Chandigarh could interest you (if not Mrs Meltwaterfalls!). Overnight train up there from Delhi (saving a hotel too) and you could do it in 1 day return (such a train journey is an "essential" part of the India travel experience anyway). It is around 250 kms from Delhi - the overnight trains go "slowly"! Choose the train which starts in Delhi not the ones which have come up from the south as they can arrive rather late - especially in the winter mists of N India. Alternatively a 3.5 hrs evening train from Delhi with prebooked hotel in Chandigarh.
Another day and you could take in the nearby Kalka - Simla railway. (Another 115kms all the way to Simla). If you only went as far as Kalka, (plus a bit further i guess if you went by taxi - but the whole journey is a slow mountain road taking 3.5 hours) from Chandigarh you could take it in on the same day as Chandigarh and still get back to Delhi that evening. Kalka is less than 30 kms from Chandigarh. You would miss the delights of the journey up to Simla of course and the colonial ambiance of the town. I should mention that, IMO having visited all 3, this is the least interesting of the mountain railways - behind Niligiri, with Darjeeling the best. But still worth seeing. You need to consider your likelihood of taking in one of the others "one day"!

I had looked at Chandiagrh and Simla, it still may be an option, though I think Clyde's recommendation of just taking our time a little more may be more the direction we are heading, spending extra time in Mexico City a few years back rather than squeezing in some additional sites certainly paid off for us, and we are hoping that a similar approach to Delhi may prove worthwhile, but thanks for the other options.

The idea of visiting Chandiagarh itself doesn't really fill me with joy (despite my defence of the leCorbusier inscription, his work isn't my cup of masala chai), but I would be interested in seeing it. Riding the train to Simla though would be great though certainly appeals so perhaps it is worth squeezing some of the other items on the itinerary down a little.