A big benefit to flying Xiamen air is that if you have a layover of 2-6 hours or more, you get your choice of hanging out in the Transfer Passenger Lounge, a free city tour, or a free hotel.
No matter which you choose, you go to the Transfer Service desk just next to the domestic baggage carousels on the first floor (turn right outside the international baggage). It is very easy to find. There are three lines, each marked (in Chinese and English) for Hotel, Passenger Lounge, and City Tour. When I went, only one gal spoke a few words of English but you don't really need it. Just give them your boarding pass and passport and they will hand you a voucher and point you in the right direction.
LoungeThey will point you downstairs just in front of the Transfer Service desk. You just have to keep looking for the signs and you will find your way to it.
On my first trip through Xiamen, I decided to hang out at the lounge. I figured a glass of wine and some snacks might be nicer than a few hours sleep in a hotel and I was a bit too tired to enjoy a city tour. Mistake. It's not much more than a comfy seat and WiFi (Chinese WiFi mind you so no Facebook or Google).
There are a few lounger beds in the back (which stay pretty full) and a row of massage chairs. The gold plates on the floor slide open to reveal electrical outlets, and there are others scattered throughout. There's Nescafe, a few cans of soda, some soda crackers, and pickled tofu packets. So much for the wine and snack I was hoping for!
It's a hop on hop off kind of a thing. I haven't done this one yet. I overheard the woman at the Transfer Service desk tell someone they can do it in 2 hours, but I also heard second-hand from a traveler that used up 8 hours of their layover on the city tour. So if you don't feel the need for a shower and a nap, this could be a fun option.
HotelI think it depends on the hotel they are using that day, but expect to have to share your room. So that means if you are traveling solo, you share with a random stranger. Yeah, that can be kind of weird. If you befriended someone during your flight, you can ask to share with them.
You have to take your own taxi to and from the hotel which costs approximately 15 Chinese yuan ($2.20 US) each way and you must pay in the local currency. There is a money changer just down the hall, ATMs upstairs (you probably only need about $10 US unless you plan to shop), and the taxis are right outside the door next to the Transfer Service desk. Show the taxi driver your voucher for the hotel address as they will not speak one word of English and they will also try to short change you. The hotels are close to the airport so although you might want to allow time for traffic returning to the airport, I had no traffic at all at 7pm.
The hotels are nice. The one I stayed in was the Hezheng Hotel on Fanghu North 2nd Road. The halls reeked of cigarette smoke but the room was nice with a kettle, waters, toothbrushes & toothpaste, and WiFi.
It was wonderful to have a shower, get some sleep and have a wander around town. Even though it's an industrial city, there are some amazing little Chinese local streets to roam around, have some ramen, see daily life, get lost, and have a boba tea.
See My First Foray into China - Getting to the Transit Hotel.
Go Exploring On Your Own
If those options don't suit you, you can just jump in a taxi or hit the pavement and go exploring! Once you exit the plane and are out by baggage, you are out of the secure area so you don't need to stay in the airport. Get some local currency and either know the name of where you want to go, or find someone in the airport who speaks English and have them write it down for you.
The area I found that I liked is actually a very easy walk from the airport (see map above) so if your layover isn't long enough to warrant the hotel, you can still get out and see some of the city.See An Afternoon in China.
Hang Out at the Airport
You could just hang out at the airport, but you are not allowed to check in to your flight until about 3 hours before departure, leaving your food options at a minimum. In the pre-check-in part of the terminal there is a KFC and one cafe at the opposite end. You do only need a passport to get into the International check-in area where there are a few more food options, but nothing spectacular. It's mostly just duty free shops.
Once you are past security into the gate area things look a little less bleak. There are even more options including a Burger King and a cafe that sells cans of warm beer. There are fresh OJ vending machines (yes, full of real oranges and they smell wonderful when you walk by) and free water refill stations! They dispense hot and cold water so if you have something like cup-o-noodles (which you can buy at some of the souvenir shops), you have yourself a hot meal. And if you have enough of those warm beers, you might just be tempted to use one of the karaoke pods!