I stopped regularly checking bags 24 years ago, when an airline lost my bags in the midst of back-to-back job interviews, leaving me wearing the same suit for 3 days straight.

Since then, I travel with carry-on only whenever possible, regardless of the trip duration. I routinely make 3-week trips throughout Southeast Asia without checking a bag. Yes, it requires sacrifice and planning, but it's well worth the freedom of not having to worry about my bags and their contents. Another advantage is that I can easily do standby (or change flights in the case of IRROPS), because I always have all my belongings with me.

I generally pack the same things for a 3-day trip as I do for a 30-day trip; for the latter, I do hand laundry every few days. (Unlike lhgreengrd1, I find that I can pack lighter when I go to colder destinations, because I don't sweat as much and thus don't need to change clothes several times a day.)