The Watania Sleeping Train is a fairly convenient way to get between Cairo and Luxor/Aswan, the main destinations served by this train. General information on the trains can be found at http://wataniasleepingtrains.com/Watania/Price_list_%26_Schedule.html, although this site has some access problems and is not overly reliable. You can also get the same general information and book your tickets for this train online at http://e7gezly.com/sleepingtrains/. This site tended to work much better and seems to have more up-to-date information.
Online booking process: tickets for the Watania Sleeping Train can be booked online at http://e7gezly.com/sleepingtrains/#get_tickets_div. The site is fairly easy to use and requires a credit card to place your order. There is a 2.5% booking fee and a 3.0% credit card fee added to the ticket prices. For foreign citizens, prices are US$80.00/adult (US$84.46 with fees) for a single cabin, US$60.00/adult (US$63.30 with fee) for a double cabin (prices are per person), and US$47.00/child (US$47.47 with fees). Prices include dinner and breakfast served in your cabin. Once you select your travel date, the site will show you the departure cities and trains (one-way or round trip) that are available for that date. After you complete your order on this site, you will simply receive a notification that "Your order was successfully created, thanks". After a few hours, you should receive an e-mail with the subject message "Your order at E7gezly.com has been completed successfully". This e-mail contained a summary of my order along with a note that stated "You will receive your ticket within the next 2 hours". However, this first e-mail already contained a PDF file that was to be used as the actual ticket. You will need to take this PDF ticket with you on the train.
At The Station: on the ticket, you are advised to arrive at the train station and be on the platform at least 30 minutes before your departure time. Note that this does not mean that the train will operate on time. On my trip, the train was at least 30 minutes late leaving the Giza station and arrived nearly 2 hours late into Luxor. I recommend that you factor this possible delay into your travel plans. At the Giza station, there are a few small shops to buy snacks or water, as well as a small restaurant. Keep in mind that this train does serve dinner and breakfast. When you get to the Giza train station (which is next to the Giza Metro stop), there are small numbers hanging from the platform canopy. These numbers are intended to indicate the approximate location of the wagons. So, if you are in Wagon #6 on your ticket, line up by the #6 sign. Note that this station handles both the Watania Sleeping trains as well as other local trains. Do not panic if at your scheduled departure time, you see a rather rough looking local train (see my note about delays). Do not board this! Wait instead for the sleeping train, which is green and white colored and has the words "Sleeping Car" stenciled on the side.
Scam alert: when you get to the Giza station, like most of the other tourists there, you will probably wander around the platform looking for any Watania sign or staff member. You will not find one. It is best to simply wait for your train on the main platform with everyone else. You will likely be approached by people with official looking notebooks offering to help you and they will ask you for your ticket. Do not show anyone your ticket. What these people do is to write down your name and destination from the ticket as if they were verifying your ticket. What they do instead is to call ahead to their buddies (i.e. in Luxor) and provide them with this information. When you arrive in Luxor, you will then be approached by people claiming they are there to pick you up (using your first name). This is a basic taxi and hotel scam. I recommend that you pre-arrange your hotel or pickup in either Luxor or Aswan to avoid this scam.
On The Train: once the train arrives at the platform, Watania personnel will be in front of each wagon to verify your ticket and make sure you get into the right wagon/compartment. The onboard staff are generally very friendly and helpful. Wagon numbers are posted just inside of each wagon entrance (not anywhere outside the train). Compartment numbers (shown as Bed No. on your ticket) are posted on the compartment doors. Note that if you are in a single cabin, you will only have one of the two compartment numbers on your ticket. There is no toilet in the compartment, instead you need to go to the end of the wagon. Inside each compartment, there are two fairly comfortable seats with a small center console between them. The compartment also has a small sink area with a mirror where you can freshen up. There are lighting and air conditioning controls next to the entry door, as well as a small area to hang up a few items. There is not a lot of space for luggage in these compartments. The seats, and the panel above them, fold down to become the beds after dinner is served. The purser will come to your cabin to do this for you. The foam mattress is very firm with decent pillows and bedding. After the train leaves and people have generally settled into their compartments, the onboard staff will bring you your pre-ordered dinner (as selected when you book your ticket). The meals are similar to what you would get on an airline, although fairly heavy on breads/starches. Breakfast is served about one hour prior to arrival at your destination (again, heavy on bread).
Taking the Watania Sleeping Train is certainly cheaper than flying and at a minimum you save on one nights' hotel. However, do not expect the same level of smoothness as a European EC/IC overnight train. The rails in Egypt are not great and there was a significant amount of jostling and vibration in the train from the tracks. Overall, though, this is not a bad option to get from Cairo to Luxor and/or Aswan.