I live in the USA and also dislike the tipping everywhere custom. Give yourself this comfort, though. There is no custom. Tipping customs are all over the place. And those receiving the tips act awkward in receiving them as do those who fumble tipping. Don't overthink it.
For me - $1/bag at a hotel. But I never let them take my laptop case.
Taxis - 10% of the fare, unless they SUCK.
Restaurants - 20% of the bill.
Drinks - $1/each
Valet - $5
Front desk - never tipped. Hotel maids - only in London and Egypt. Doorman - nope - never even thought about it. Tip cup at the sandwich shop. You must be joking.