How is the treatment at DT BEIJING for bookings by Gold members ?
Hows the breakfast spread and EL servings ?

When did it move up to cat 2? Was it ever announced?

It was hit and miss. Upgraded to suite several times as Gold. But also knew Diamond didn't get suite upgrade in the past.

Didn't stay at Cat 1 for long (a few months) before moving up to Cat 2.

No announcement from Hilton? I thought cats usually get adjusted as part of a deval or annual adjustment. Didn't know they happen secretly.

How long does it take to get to the DT from PEK? Someone on Trip Advisor said it took 90 minutes, but the hotel website says 55 minutes. I assume that it may depend on the time of day. I will be flying in from Xian, but have not booked the flight yet. When would be the best time of day to arrive?

Late evening / night would be easiest. The later the better, arrived once at 1:30am and was a breeze :-). Very early morning also works well but usually this is more useful for departures. Avoid rush hour traffic in the mornings and later in the afternoon, early evening.
So in summary either around lunch or later in the evening after 8 or even 9pm (which can be a bit tricky because flight delays tend to get worse as the day progresses).
Depends also a bit what you plan to do in Xian, if you plan a full day there might as well fly out in the evening and head straight to the hotel to go to bed.

Take the train from xi'an. Beijing West is close to the dt.

Traveling in eastern parts of China is very convenient with the high speed trains.

I never considered a train. How does the total travel time on the train (Xian station to DT) compare to flying (Xian airport to DT)?

The fastest trains on that route do it in around 4.5 hours. Meanwhile airplanes spend less than two hours in the area. However, a number of factors eat up that 2.5 hour advantage pretty quickly.

Overnight trains are also worth considering. These are much slower, but that'a good thing (more sleep time).

Thanks. I'll take this into consideration.

Just an FYI, although taking the train can equal more sleep time en route, it is also an extreme hassle getting on and off the train, especially at Beijing West Railway Station.

You will find that at railway stations, compared to airports, service staff are much fewer as a ratio to passengers, as well as having much less experience interacting with foreigners. Meaning that if you need any help it will be difficult to find it.

Depending on the time of year your planning this trip as well, it could be busy, and its not out of the ordinary to be waiting for a taxi at Beijing West (in the Taxi queue) for over an hour.

The prices are not exactly cheap either. For the "Gaotie" which is the high speed rail, it takes between 4h40m to 6h12m to get from Xi'an to Beijing, and the price for a "first class" ticket would be 824.5RMB. These seats are about the same as American regional business class seats on an airplane. For the sleeper trains, the trip time is 11h15m and costs 415.5RMB for a "first class" cot, which is a bed that is cushioned (slightly) in a private room for four (unless you have three companions, this will be in a room of strangers over night).

For a plane ticket, Xi'an to Beijing one way fares in late August are running from 650-1100RMB, so the price is around the same as the high speed train. You will end up arriving at the airport which geographically is much further from the Doubletree, but it is MUCH easier to get a taxi, as well as just having less crowds to deal with.

That being said, if you do decide to take the train, especially if it's going to be the overnight train, make sure to spend the extra (I think 30RMB, about $5 USD) to use the "VIP" Lounge. This will allow you to board through a side corridor, avoiding the CROWDS, and at Beijing West, there will be crowds.

For the other two train stations it is actually a bit better (avoid Beijing West like the plague). There is Beijing Station which is right off Tian'an'men Square and relatively small, making it easy to exit. Also Beijing South which is almost like an airport (new station), and quite intuitive to navigate even if you've never been there. Unfortunately though, none of the Beijing-Xi'an trains leave or arrive from either of those stations, and your stuck with Beijing West.

Conclusion: Take the plane, even with possible delays and longer distance from the hotel it is just less of a headache. Beijing West is a big and messy station. I as a Chinese Native, who speaks and reads the language have a hard enough time navigating that station.

Either way, good luck with your trip!

Welcome to FT, and your analysis is great, but IMO the DT's distance from PEK tips the scales in favor of the train from Xi'an.

I welcome you to FT as well. As you mentioned, the price for a good seat on the high speed train is not cheap. I, on the other hand, am cheap and have opted to use 15k UA miles and fly to PEK despite the distance to the DT.