Apart from a diamond pickaxe for obsidian, and a steel sword, I use stone tools exclusively. It's a renewable resource and I have plenty of time (why are you playing a timesink like Minecraft if your time is valuable?). I save my iron for things that need it, like shears and iron bars.
EDIT: Just occurred to me - I play mostly on SMP servers, so the availability of ores is slightly different to those of you playing single player. I have to travel some distance for good mining areas.