Wondering... Which of these might be best re efficiency, cost and ease of travel...

1. Beijing -> Xi'an -> Chengdu -> Shanghai -> Hong Kong
or
2. Beijing -> Chengdu -> Xi'an -> Shanghai -> Hong Kong
or
3. Beijing -> Shanghai -> Xi'an -> Chengdu -> Hong Kong
or
????

It is also possible that I might drop out Shanghai altogether. I am not a big city person, prefer nature and animals. I do want to see the Pandas, but given that I do have 3 weeks I should have time for all of the above, yes?

Also - trains/planes?
1. Train first leg, Beijing -> Xi'an and fly others? Or possible train also Xi'an -> Chengdu?
2. Train Chengdu ->Xi'an and fly the rest?
3. Train Xi'an -> Chengdu and fly the rest?

What about costs? Are there any sites on the internet that I can get rates for these flight/train possibilities?

Any other ideas that I don't see in the above? Buses? I don't want very long train trips - I get restless and walk the aisles on even a 4 hour flight, so no 24 ++ hour train trips please.

BTW - are there discounts for age in China?
Thanks!

There are several questions in your post, but I'll answer it in a different way.

First, there are many more non-stop flights from Shanghai to Hong Kong than from Chengdu to Hong Kong. Cost similar, so I won't recommend option 3.

Now whether you should do 1 or 2...

If you're going to fly mostly, then really no difference. But if you want to take the train, then here are some train times:

Beijing - Xi'an. Overnight, 11.5 hours.
Xi'an - Shanghai. Overnight, 16.5 hours.
Beijing - Chengdu. 26 hours.
Chengdu - Shanghai. 35 hours.

Based on those numbers, if you want to try some train but not too much, you can train Beijing-Xi'an, and then fly Chengdu-Shanghai.

Now, as for Xi'an-Chengdu, fastest train takes 13.5 hours (it's actually a Beijing-Chengdu train); other trains about 16.5. But here's a dilemna - it's a scenic mountainous railroute; so it'd make sense to take it during daytime. But you have to start really early to get on that Beijing-Chengdu express stops at 5:16am. Or you take one of the overnight, and miss most of the scenery. Might just want to fly between those two.

Another consideration is that a soft-sleeper train ticket is about the same price as a discount coach. So, you don't really save money, unless you want to take a hard-sleeper.

Updating and changing...
Have been strongly advised that Shanghai is really "just another city" and that I should try to get out into the countryside a bit, or at least to a small town.

Is there anything in the Xi'an, Chengdu area that would be worthwhile for a first-time visitor to China? I like to walk, not trek, just walk for a few hours at a time and like nature, scenery, animal life. Not interested in cruises.

Thanks.

rkkwn,
Thanks for all of the great info!
Someone suggested the night train Beijing to Xi'an and then another night train onwards to Chengdu, fly from there directly to HK.
If I understand you correctly this means either spending the night at the train station (is this possible?) or missing the beauty of the ride...

You said "soft-sleeper train ticket is about the same price as a discount coach." By coach in this case you mean flight, not bus? How about a soft seat in the early am? Is that also as expensive?

Do I have to stay in my car, or can I walk the length of the train back and forth? Like I said earlier, I get restless even on a 4-hour flight :~0

Thanks!

There should be plenty of areas outside Chengdu for hiking. Chengdu is at the edge of a basin with very high mountains just beyond it. However, I don't have specific recommendations for hiking.

As for the train, the Beijing-Chengdu express is unlikely to carry any soft-seat cars, as it's a long-distance train. But during the day, they can fold the upper-berths of the soft-sleeper, so it becomes a cabin for 4 seats. I don't know how the ticket works.

Yes, I do mean soft-sleeper cost about the same as flying in coach. If you want the cheapest way to go, then get a hard-sleeper.

On the train, you can move around and go to the dining car. But you won't want to linger at the hard-sleeper or hard-seat cars.