If service charge is included I have never tipped because I don't think they should automatically add it. Never used room service (only on cruises where its free food and only tip a few Dollars) Everyone else gets minimum wage or above. Its personal choice. Some tip for a taxi being called, or a suitcase being picked off the floor into the trunk, I dont, I am capable of doing it myself, I dont ask them to do it, they do it and expect tip.
My Uncle won't tip a cent to anyone, I tip Waiters, Debbie tips everyone, its what you are comfortble with yourself.