I hope you mean adapter: An adapter changes the plug configuration so your US power plugs fit into the wall socket in the foreign country you are visiting. A converter changes the electricity so you can use your NON-DUAL-VOLTAGE appliances when visiting a foreign country.
How "normal" is it to find 110 current in a European hotel?
Do people have recommendations on converters?
We have pre in the Italian lakes area and post in Istanbul and would like to be able to recharge phones, use electric toothbrushes, etc.
I'm with you. I buy t-shirts everywhere I go and have lots of what I consider to be nice ones. One of my favorites is a Minnesota Kicks (tried to get soccer going in the late 70's) which reads "It Takes Leather Balls to Play Soccer."
At the Ratskeller in Regensburg I was drinking a dunkel that the monks at Kloster Weltenburg have been brewing for over a thousand years. That part of the world is heaven to a beer drinker.
Have Oliver Zinapold in Triberg (https://www.olisschnitzstube.de/en/) make you a cuckoo clock. Then you will have an authentic/traditional/classic Black Forest cuckoo clock rather than some tourist tat.
Most of the tipping I saw being done on Homelands was in $$$. I believe the $$$ are easily converted to local and gladly received. I have heard that most just wait until they have enough to bother converting.