I am travelling from HK to Beijing,and i have around 16 days.i would like to spend a couple of days in HK,Shangai and Beijing,and maybe see xian aswell.I am looking for a travel plan as i have no clue about how long to spend in each place.As regards mode of transport i am up for internal flights and maybe sleeper trains/bullet trains.I really need to be pointed in the right direction.
You can take the trains, it'll be the best way for you to get around and see the country.
If you want to fly, you can sometimes find cheap flights, but sometimes they can be expensive.
The benefit of taking trains is that you can sleep overnight on the train and wake up at your destination. Train stations are much more conveniently located than airports generally, and much easier to get in and out of. If you're friendly, you can even meet lots of interesting people on the train.
You'll usually want to buy the ticket for your next leg when you arrive at the station. It just saves you a trip back to the station later. You can usually use English or a guidebook to get your point across and buy a ticket without speaking Chinese. However, the best option is to be friendly and ask if anyone around speaks English. More often than not, you can find a friendly Chinese person to help you buy the ticket.
On the train, be sure to take soap and toilet paper. Also, you should try to take plenty of snacks and drinks on the train. The stuff they have for sale either on the train or at the stops is pretty lame.
From HK, you can take the train to Xi'an. Spend a couple of days there and see the sights (don't miss Hua Shan).
Then take the train to Shanghai, and from there to Beijing.
In Beijing go to the Forbidden City. Don't get a guide. Read up online, get a map when you buy your ticket, and plan to spend all day there. Don't rush through it, you'll miss all the interesting things.
Also be sure to go to the Great Wall and Summer Palace. Don't join a tour group, just hire a private driver to take you. From Beijing to the Great Wall and back you should be able to get a private car (most hostels can help you arrange it if you need) for about 400-500 RMB. That's round-trip, all day. It used to be possible to get a car for the whole day for as cheap as 350, but that's getting pretty tough these days.
In the interests of saving time, you might want to fly, at least part of the way. But it's usually cheaper to get a flight from Guangzhou or Shenzhen (across the border from Hong Kong) than from Hong Kong itself.
As far as time goes, I'd suggest:
Hong Kong: 2 days (unless you really love shopping).
Shanghai: 2 or 3 days.
Beiing: 3-4 days are needed (one day for the Great Wall and Ming Tombs, one day for the Forbidden City and Tiananmen Square, one day for the Summer Palace and Olympic buildings, and one day for just looking around).
Xian: 2 days are sufficient (one day for the terracotta warriors, and one day for the city itself).
Hong Kong is an amazing place but make sure you get away from the main part of the city. Try to get a ferry, southern part of Hong Kong Island, and go to Lama Island. Lantau island is also really nice. A night wandering around Kowloon is definitely worth it as well. Shanghai is nice but you don't need a ton of time there and with the expo it is going to be uber crowded and more expensive than usual. The old French Quarter is a really nice place to wonder around. There is easy public transportation, not as full as HK but good. Pudong and the Bund are obviously places worth visiting. From Shanghai you should go to Suzhou or Hangzhou, beautiful places, lots of gardens and streets weave through the towns.
Beijing is a wonderful place but really takes a few days to get a real feel for the place. If you are into art, 798 is a huge complex with tons of galleries. http://www.798space.com/index_en.asp. Sanlitun, 三里屯, has a lot of stores, restaurants and bars. It is a wild place on the weekends. Houhai, 后海，is a great place too. It is easy to find on a map, big lake, during the day it is a nice place to walk around, and at night the whole place is light up with red lanterns in front of bars and restaurants. Don't go to any of these bars, they are overpriced. There are a few worthwhile places though. If you like jazz check out East Shore, 东岸，live music Thursday through Sunday. Nanluoguxiang is a pretty nice street too 南锣鼓巷, it is between dianmen dongdajie,地安门东大街 and guloudong dajie 鼓楼东大街. Some other good places to see live music, often local bands, sometimes foreign or expat bands, is Mao Live house. It is across from the north entrance to Nanluoguxiang, on guloudong dajie. The normal sightseeing stuff like the forbidden city and the temple of heaven are important of course. The summer palace is also really worth it. The best section of the Great Wall was just closed for some repairs, Simatai. I would recommend either Mutianyu or Jinshanling. DO NOT go to badaling. It is terrible and way touristy and crowded. You can usually book a trip to jinshanling from a guest house.
Xi'an is nice but doesn't need to much time itself. The Muslim quarter is excellent, colorful and animated. Great street food too. The big goose pagoda is worth a stop, lots of history there. The famous story, Journey to the West, about the Chinese monk Xuanzang and his retinue, including the impish and powerful Monkey King is based on the real journey of a monk that left from this monastery in Xi'an. In my opinion the Terracotta worriers are a waste of time and money but it is up to you. The best thing around Xi'an is Huashan. If you enjoy hiking this is it. Incredible views from the top. Stay at a guest house on one of the summits and get up to see the sun rise. The hike can be harrowing if you start from the bottom at the Soldier's Trail but there is also a cable car that takes you most of the way. The bus leaves from the Xi'an train station daily around 7:30, maybe. Check with the time. You want bus 303.
It is up to you whether you want to take your 16 days in China and cram as much as possible in or take in only a few places and get to know them better. It depends on how you like to travel. Personally, I enjoy spending more time at fewer places as opposed to less time at more places. Good luck with the journey.
Hong Kong is a great place to visit, places that i recommend: disneyland, peak, ocean park, tst victoria harbor, causeway bay times square, Lantau Island, night market, lan kwai fong. Hong kong is amazing if you love shopping, clothes, purses, shoes, etc are cheaper in hong kong because theres no tax. And if youre bored of Hong Kong, you can also spend a day or two in Shenzhen and Macau, its really close to Hong Kong. You can get to Shenzhen by the Subway and Macau by ferry. In Shenzhen, you should definitely spend some night time in Shekou Sea World square, there are many restaurants and bars there. Also Windows of the World or Splendid China can be interesting for an afternoon excursion. If you wanna do more shopping, i recommend you to visit China South City where theres various of gifts, souvenirs, fashionable clothes, shoes, purses in reasonable prices. And of course if you want to gamble go to Macau and there will be casino everywhere like Las Vegas..hope this helps have a fun trip!