Clarion Hotel Arlanda

You really have two options in ARN — this or the Wyndham. There are cheaper hotels outside of the airport, but who wants to get cold during the winter?
I have stayed at both Clarion and Wydnham and I prefer Wyndham by a longshot. Not only is the breakfast better, but the staff is also friendlier as well. Heres the biggest bonus though — the restaurant and lobby lounge has a nice selection of local beer ;)
The staff has always gone out of the way for the wife and I. We were traveling for a few weeks and they were able to do a bunch of smelly laundry, at no cost!
As many others have pointed out, the rooms are quiet. Even though some face the runway (AV Geek dream) there is literally no plane noise.
Stay here, forget the Wyndham!
DO note: its about 45 minutes to downtown, at a cost of roughly $ 40 usd round trip. If you want to go downtown, this may not be the place for you.

Stayed the night before flying back to the US. Hotel was aesthetically pleasing and very relaxing. Being connected directly to the airport, we were surprised at how QUIET it was. Rooms were well appointed and were well stocked with everything we needed. Ate dinner at Kitchen & Table and had a fantastic meal, however, if you are looking for a more budget friendly choice, there are plenty to choose from in Sky City. Bar is open until midnight (great patio!), pool is open until 930 pm.
Breakfast was included with the room price and it would be hard to find better. Omelet bar, fresh fruit, juices, yogurt, meats and cheeses, eggs… etc. Great selection and everything was very good.
Service at the hotel was top notch, from the front desk to the staff at the restaurants and bars.
The hotel has a gym which looked quite nice and clean (I was on vacation, so I didnt use it =))
Price wise, I dont think we could have found a better deal! Thanks so much!

Excellent airport hotel. In the terminal, but not noisy. They also have a gym, great bar, and pool. Very new and modern. Great wifi.

I stayed here one night at a decent cost. The hotel is very easy to get to from the terminals, staying indoors all the time (through Sky City). I heard no airplane noise, so the windows must be well insulated. Very efficient air conditioning and the room was on the cold side; unfortunately I didn’t quite figure out how to change that. The bed was pretty nice and the room was equipped with what you needed. Nothing very fancy but fine. The room was small but just large enough not to feel cramped. The breakfast was above average for Sweden, meaning that by international standards it was very good. The bar was open until midnight on that Saturday evening, though last call was around 23:40. It was small but had what you needed. The free wi-​fi worked fine on both computer and phone (let them know how many devices you need when checking in, as you get separate codes for each). Tip: each code lasts for 24 hours and also works in the rest of the airport (and in many other hotspots around Sweden), so make sure to make full use of it. Close to four stars, I might reconsider if I get to stay here again.