There were many electric doors or gates that open only in one direction so there is very little chance of getting lost in the airport, you just follow the signs. Just a note, at the immigration, my passport was stamped while my wife's was not. Though we ask the officer for it to be stamped, he just asked us to move on (in a rather unfriendly manner); not sure if he misunderstood us or what. Later when on our way back home, the immigration officer was searching for the entry stamp in my wife's passport and he said that it should be there. Luckily, I had put my wife's incoming flight boarding pass stump together with her passport to prove her legal entry into Germany, just in case. So if you come across similar situation, do the same; it will save you a lot of explanation.
After claiming our luggage and making our way to the S-bahn train station down a narrow escalator, we were faced with some unfriendly looking ticketing machines. Luckily there was a DB (Deutsch Bahn, the German National Railway) office for enquiries and for ticket sales so I bought my tickets there to the Hbf, the hauptbahnhof or main railway station, at 3.8 euros each.
I started looking for the hotel after getting off at the Hbf and before I could ask another DB service counter, I saw the ads for the hotel right on the wall above the side exit of the station. It was Hotel Excelsior, just 20m or so across the side entrance of the Hbf. This is the best location for a hotel if you are arriving at the main railway station and it turned out also to be the best value for money among all the hotels that I have stayed in Germany.
In this case, I paid 73 euros including breakfast and breakfast was very satisfying with a good selection; they even have char-siew-pau and siew-mei during my stay! What's more, internet was free in the room, drinks in the mini-bar are also free and they even have light refreshment in the lobby (coffee and cakes) for customers during the day. No other hotels can beat this and this hotel is highly recommended. This may not be in a choice neighbourhood or the tourist area but it is easy to get anywhere with its central location just next to the main transport hub where the S-bahn, U-bahn, trams and buses meet.
These are the goodies in the mini-bar, 2 of each, all FREE!
The check-in counter staff was very friendly and after a shower, we went straight to bed as it was about 10.30pm local time so that we will be fresh and ready for the next day.
Just a word about the prices of hotels in Frankfurt, it can go up a lot during trade fair seasons so check when you are staying there as there are many trade fairs throughout the year. You can save quite a bit on hotel bills by just changing the dates of your travel. I chose my hotels by reading reviews in tripadvisor.co.uk and did all my hotel bookings online through booking.com which seems to offer the best prices. It is easy to use and you are not charged until your stay or default for not turning up so you can make changes where necessary. (But make sure you cancel the earlier booking.) If you expect to arrive late (i.e. after 6pm local time), do inform the hotel so that they will keep the room for you.