Sometime it seems we can't pack enough, but in the end, we mostly have too much. For the last 20 years, we have been buying 25" Samsonite or similar and keep it around 47 lbs, and are never 50 lbs or over. We not only do this for leisure travels, but we lived in Asia for total almost 13 years, and came back to US quite a bit, and 25"er was fine. If going to cooler climates, we layer and sometimes have 5 sweaters, but I keep these to the lighter style and use long sleeves for under; can always take off. We learned to stay away from jeans as they are heaviest; I changed to stretch jeans and find them much lighter, and I even wash them after 3 washes; they dry fastest. There's many comments elsewhere on wearing jeans 4-5 days, but I don't know.... I keep to 4 pairs of pants/jeans, 4-5 jerseys, 3-4 sweaters, london fog type raincoat, lined/water resistant windbreaker, hat, 2 pairs of walking shoes. If on river ship, I take one pair very light dress pants with 2 "dress for success" type tops and dress sandals; mostly we wear to dinner what we wore all day anyway--mostly everyone else does. We even carry "what if" bags, i.e., cold/cough medicine in gel caps or tablets, intestinal tablets for whatever ails us, headache/ allerg remedies, mosebleeds, nail clippers , scissors, bandaids, small stapler, small scotch tape, post-it tabs; this in addition to our prescribed medications. I throw in a clock, long scarf, gloves, travel iron, curling iron, noto mention before my e-reader, 4-8 paperbacks. Still, if I'm just at 50 lbs, I take out one jersey and 1 sweater and 1 book. I tested several sweaters I have to see which is warmest and dries fastest if I washed it in a sink. Acrylic/polyester dries the fastest, and is lighter, but warmer than cotton. Cotton takes the longest to dry (before river ship laundry, drying cotton sweater aboard was 3 days!). I have learned to pare down my toiletries to travel size; it's easier to fit two small tubes toothpaste around something else, than one larger tube you'll end up taking home; I like my own shampoo, so I use small bottles from something else to fill with my own shampoo (I use two diff. kind shampoos, too). I like convenience, so this is not all I take. But am never over 50 lbs with my 25" case.
In 1999 we flew from Singapore to Australia, taking internal flights 3 times within Australia. Quantas personnel walk the que line looking at bags. My husband had a backpack that was full, with 3 cameras and a laptop, jacket, etc.. He was told to take out the laptop and they would check it for him. Luckily I had room in my backpack because I had lighter stuff, so he didn't have to check it. They weighed our backpacks, and for those using wheeled carry-ons, they were placed in the sample size at the gate, and many weren't allowed to take on. That was internal flight. They are strict.
I know I've rambled, but I've just found ways to be comfortable, look neat and clean, and not over-tax ourselves lifting the bags off a carousel.