Spend your 3 days in LA and then fly to Las Vegas. Do not drive through the Mojave Desert. I'm not sure you can see all three National Parks you mention since there may be snow in at least 2 of them. The Grand Canyon South Rim is closest to Las Vegas with a rental car.
Fly from Las Vegas to San Francisco. Take the Coast Starlight train from SF (Emeryville) to Portland. You have a lot of good choices for your skiing including Mt. Hood near Portland.
If you want Colorado skiing, fly from Portland to Denver. Fly to Washington DC (or BWI) Use Amtrak trains between Washington DC and Boston including NYC. You might be able to get to Yosemite from San Francisco but don't count on it in mid December.

A couple of notes:

You will be in a lot of winter weather - so be sure you either pack or buy the appropriate clothing - not just for skiing but for winter in the city. NYC is about 100 miles south of the snow zone - but we can get heavy snow as early as Christmas - a couple of years ago it was 2" and several years before that about 12" Boston will have more - and depending on the path ofhte storm DC may have almost as much. Storms that large - 2" - will play havoc with flight schedules and can also stop the trains (a lot of wet heavy snow and wind will bring large trees down across the tracks - besides clearing huge amounts of snow - and driving is not something to try unless you're expert in those conditions. In center cities you are fine - since you can walk and typically subways still run. But getting to another city can easily be delayed 2 or 3 days. This weather is unlikely - but certainly possible.

Also you will be in NYC at the most expensive time of year - NYE can easily double hotel rates. So I suggest you get reservations as soon as you have fixed your dates to have a chance at whatever comparative bargains there are (unless your budget is unlimited).

Also, do realize that Las Vegas and Grand Canyon are also in winter - and some of he roads through the parks and over the mountains close for the winter (due to feet and feet of snow). If you hit only good weather you can probably keep to this schedule, although it is rushed except for NYC. But if you get bad weather you could be up the proverbial creek. I would bild a little flex time into your itinerary in case that happens.

Sorry - that first storm was 22" - as in 2 feet.

See the Boston pops holiday concert.

Check out the rockettes at radio city in ny.

Thanks guys. Those national parks don't have any winter attraction? How about the colorado river cruise? What else is there to do in those cities?

Cheers

If you do Yellowstone, plan on skiing in Utah - the Park City area. It's only 45 min tops from Salt Lake airport. But, as others have said, snow could be so heavy that airports will close as may the parks. On the other hand, it is early for ski season and some areas may not be fully open. It's a gamble. I also think trying to do those 3 parks in 3 days is very ambitious. Lots of driving in possible bad weather and rds may be closed. I think the Colorado rafting trips are only done in warmer weather and I have read that reservations need to be made way ahead.

As for the cities, all will be crowded and expensive around the holidays but full of activities - special shows, decorations. Boston has First Night New Yrs Eve with performances, ice sculptures and fireworks. Just do your research, check out driving distances, flights and trains and make your plans accordingly. Always good to have a Plan B in the winter. Enjoy.

Awesome! I think I am getting the big picture.

You can drive from LA to Vegas in about 4 hours - but it's also easy to fly. From there - you can take a one day van tour of the Grand Canyon - or a plane ride - or drive yourself - about 5 hours or so.

Once in the Northwest - Portland - since you are only considering a couple of days of skiing - you might consider skiing at Timberline Lodge on Mt. Hood. http://www.timberlinelodge.com/

Unless there is a very big storm, it's usually an easy hour or so drive from Portland. It's a beautiful place to stay and decent skiing, and since it's a glacier - they ski (and teams train there) even through the summer months.

It all depends on how much challenge you want. If you want more challenge and they have enough snow - Mt. Bachelor in Bend will be just fine, http://www.mtbachelor.com/summer/index.html or the lesser known but quite challenging Crystal Mountain on Mt. Ranier - outside of Seattle. http://www.crystalmountainresort.com/

You could also zip up to world class Whistler/Blackcomb - outside of Vancouver, but that's more work for just a couple of days. http://www.whistlerblackcomb.com/usa/index.htm?campaignid=google-us-lodging-b-general-b&s_kwcid=TC|9174|whistler%20blackcomb||S|e|12223270095&gclid=CKHe7crV4bACFQF6hwodWFAf2Q

Again, depends on how much snow they get in Dec - but Timberline is just about always open for some skiing.

Other than skiing in the Northwest - I too second considering Park City. Easy to get to from Salt Lake City (an hour driving and they almost always have the roads open)- and rarely is that airport closed for very long.

Plus they get the most powder - except for Grand Targhee in Wyoming, the "front side" of Jackson Hole.

If Denver gets a big drop - they can also experience airport slowdown/temporary shutdowns, but then you also have to go over 3 high passes to get to Vail or even further to get to Aspen - unless you try to fly into Vail or Aspen.

And getting plane reservations to Aspen (small - high altitude airport) would be more challenging the closer you get to the Holidays.

I would also consider adding another day in DC - as there is a lot to see there, such as the Smithsonian, and other art and science (Natural History, etc)museums. Plus Georgetown has some good nightlife, whatever.

And yes, get your NYC reservations as soon as you can. Very busy time in the Big Apple.

BTW - as for a 3 day trip to the Grand Canyon, Yellowstone and Yosemite - those are really quite a distance apart, even by Aussie standards.

I am a big fan of all 3 - but I would suggest you consider going to the Grand Canyon and then maybe enjoying someplace closer to that - such as Sedona and then fly from Phoenix to San Francisco, and plan on visiting Yellowstone (up by Jackson Hole, Wyoming and Yosemite (5 hours or more driving time from LA - 4 from San Francisco) another time.

Thanks Tomsd, definitely considering some of your suggestions.

The complication in driving from LA to LV is the one way rental car. Drop charges and mileage on a one way rental can be more than it costs to fly.

For your internal flights consider Southwest Airline. Your UK travel agent may not offer (SW does not commission travel agents). You will have to book yourself on their web site. Southwest is often the economic solution particularly for your LA to LV to SFO legs. No baggage fees, no change fees, and probably the lowest fare. SW is our version of Ryan Air.

Have a great trip! You are seeing some lifetime destinations.

Even if it snows in NYC in Dec (rare) the city will be alive and in full swing. As stated above your biggest problem will be the cost of hotels - you should expect to pay close to $300US per night including lots of taxes.

Regarding the national parks, you've not included any time for travel in your plan.

Yosemite valley is a wonderful place to visit in the winter. It's about a 5hr drive from SF (assuming it's not actively snowing). If you have 2 days you could do an overnight trip to Yosemite from SF. If there is snow then you travel to & fro can really get messed up big time.

The rim of the Grand canyon is over 6000' above sea level, which means that it'll be cold there. The average high T in Dec is +7, and the average low is -8C. It's a 4-5hr drive from LV to the Grand Canyon.

I agree that you won't have time to visit Yellowstone. At 8000' above sea level winter arrives as early as October, and by December the park will be in a deep freeze. Average high -4C, low -15C. Yes, it's a beautiful place to visit in winter, but you need a lot more time just to get to and from the park and there is far more to enjoy in the summer. Save it for another trip.

<<<No baggage fees, no change fees, and probably the lowest fare. SW is our version of Ryan Air>>>

Except that Ryan Air charges for everything, and uses way out-of-the-way airports. Southwest flies to major airports.

If you're looking for a budget hotel in N.Y. check out the Larchmont Hotel in Greenwich Village.

I agree about flying with Southwest from LA to LV - it is an easy flight but a boring drive.

If you want a road trip, you would be much better with the drive from SF to LA. Take 2-3 days for this drive, 4 is you can swing it. There is a lot of beautiful coastline to see and some neat towns. If you decide go to Yosemite, you could do SF-Yosemite-Monterey-LA by car.