On my 2 SIN runs last year, I used the shower facilities at the GYM across from the Transit Hotel (you need to pay at the hotel desk, they give you a receipt for the attendant at the GYM) to freshen up. The cyber cafe worked well and they have food (meals) for sale. There are nice cozy chairs with different big screens showing various news channel to keep you occupied unless you like to shop! And the military guard are there too, roaming the entire area. I never left the airport (went past customs) although if you want a Starbucks, you have to go out.