I switched to Continental tubes five years ago, as they don't lose as much air as other brands. I've been using them in my road bike with 23mm or 25mm tires, and they'd drop 4-7psi in a day.

Our tandem has 28mm tires, and we asked our dealer for ten tubes so we were ready for lots of riding. I was a little surprised when I saw ten of the same tubes I've been using for five years. They do lose 15-25 psi in a day, but otherwise they've held up well. (I chose a real bad line over a railroad crossing, and six weeks later we had a broken rear wheel; I'm pretty sure the RR crossing was the trigger. Nonetheless, no pinch flat with the same Continental tubes we always use.)