I always stay at the hotel Amaris when I am in Olten, its very convenient being situated next to the train station , a station where you can get to every part of Switzerland with ease.
The Hotel itself is very nice , the beds are comfortable and the shower is still the best of all the hotels I have stayed at in my own country of Austria and throughout Europe.
The only things I would love to see is maybe a carpet / rug by the bed so when you wake up in the morning it gives that extra bit of comfort , the other thing would be a kettle and maybe some coffee or teas.
But it is a great place to stay. will be back there again very soon.