Pretty much all major brands have a standard carry-on luggage size so it's very easy to stay within guidelines. I measured my carry-on wheelie out of curiosity once and all 3 dimensions are just half inch under the guidelines. Perfect.
Most of my trips, business and vacation, are within 10 days. I always take one carry-on trollie and one small backpack as the so called carry-on item and find them more than enough.
I do not check in any bags if I don't have to. And 9 out of 10 times, I don't. Easier this way. I just print out the boarding pass at home, arrive at the airport and go straight to the security gate and that's it. And after the plane lands, I don't have to wait around for baggage claim. Like it!