If you’re willing to spend a bit more, the Ultimate Ears super.fi in-ears are far more comfortable than Shure’s buds. They sound fantastic.
http://www.ultimateears.com/superfi/superfi.htm
If you’re willing to spend a ton more, UE will fabricate a custom set of in-ear phones, made from a mold of your inner ear. They seal out the outside world, to the tune of -26db, and they sound orgasmic.
http://www.ultimateears.com/custom/Custom-Ear-Monitors.htm