I'd go with a Super Tinker. They're much smaller than the Trekkers and are better for day-to-day indoor pocket carry, and add the ever-useful scissors in exchange for the saw. This is about the biggest SAK I can comfortably just drop in a pants pocket.
Classics are great because they're cheap and plentiful. But the better model is the Rambler. The blade opens away from the key ring, and it adds the super-useful mini-combo-tool that has a phillips driver, bottle opener, and wire stripper. It is only a smidge thicker.
If you'd rather have a ballpoint pen handy instead of the toothpick, the Manager is the same as the Rambler, except for that difference.
...and if you'd rather have a small LED flood light and pen insted of the toothpick and tweezers, get the Midnight Manager.
Two other models that I really like, but require belt carry are the Wenger S557 and the Victorinox CyberTool 34. Great tool selection for the size and weight.