Me again-
Trying to work on the framework of our India Christmas time trip.

As it stands we are flying in and out of Delhi (tickets are on hold) going to be in India a total of 14 days.
would it be worthwhile to hop down to Mumbai for a day and fly out back to the States from there?
thank you.

In a word, no, not worthwhile. Mumbai is short on "sights", and big and busy. Where are you spending the rest of your time?

We are going to be in Rajasthan, exactly where just in the beginning stages so not sure where yet.

any suggestions on what not to miss in Rajasthan?

With 14 days you should be able to make it to Jaisalmer, which is often skipped by people with less time. The buildings are made from wonderful golden sandstone, beautifully carved. If you're feeling energetic, you can take a camel ride, or an overnight camping trip.

I paticularly enjoyed visiting the Shekhawati area, also not on many itineraries. Public transport is problematic there, I used a car and driver from www.rajasthantravelservice.com. The area is known for its painted havelis, or courtyard houses, and the towns are much smaller and quieter than places like Jodhpur and Jaipur. My India trip reports, including Rajasthan (Deserted Kingdoms), are part of www.wilhelmswords.com/asia2002.

Skip Mumbai, you won't miss anything.

Mumbai - I like it and want to spend more time there, but I think it's liked most by people to whom it already has a lot of meaning, as it doesn't particularly have monuments.

I like it an international city like New York, where I live, which is very different form the rest of the country it's in (like New York). I like it for its restaurants and shopping, and for its comfort level for me. Places there are a lot like home, but still good and foreign.

I also like it as the home of the Hindi language film industry, which I love.

I think it really depends. Depends on what part of India you're in and what you really want to see and are interested in.

I grew up in Bombay, and so I am obviously biased. It's very different from the rest of india - food, culture, people, pace of life, the contrasts - everything.

In my opinion it has some really amazing restaurants, great nightlife, and walking around some of the commercial districts can be fun (for some). As mentioned, there is not much to "see" like Delhi's red fort and such, but the city's pace of life is something unique.

However, since you're going to just be in the northern part of the country, you may want to consider visiting it on another trip.

As you are flying into & departing from Delhi, you need not hop across to Mumbai. Mumbai, as pointed out by above posters,though, have it's own charms.
Rajasthan is a fabulous destination & offers a lot in the way of sight seeing, luxurious accomodation, beautiful temples - both Jain & Shaivite - Camel & horse riding, fine dining, boating on the Chambal, Wildlife in Ranthambhore, closing-in on black bucks in a jeep for a minute or two, luxury tented campsites to go with the general aura of the location, forts & Palaces perched atop rocky outcrops, Folk dances & puppet shows, rural destinations where you see the affable turbaned Rajput with peircing 'Getic' eyes, a lot of character writ on his weather beaten face ...it all depends on your interests & of course paramout is the development of a wonderful itinerary. The recent air connections with far off destinations like Jaisalmer makes it possible to add a bit more to your 14 days holiday.
Happy Travels!

Bombay does not fit in with Rajasthan..best avoided.