I've been hearing a lot lately about how when you're looking for a yoga mat you really want to find something thick. According to current discussion thick mats are ideal and necessary. I really don't think that's always the case, so I just have to say something. Yes thick mats are great for things like tops of feet in virasana or knees during low lunges. Thick mats have their place, but they have their drawbacks too.
I've tried a lot of different mats - some I've purchased, some I've used because they were the only thing in the studio at work, and sometimes I've gone without entirely. The thickest mats I've tried were far from the thickest available, and I think it takes no time at all before a mat becomes
too thick. If given the option of a really thick mat or nothing - I'd rather go bare.
The thickest mats I've tried have actually hurt my feet far more than the hardest wood floor. If your mat is thick but not firm then you will have difficulty balancing, and a potentially dangerous situation for wrists. Handstands, arm balances - these should probably never be done on a thick squishy mat. Some mats are thick but firm (not very common though) so they don't pose these problems and I don't really have any problem with them. However, thinner mats can be great and I prefer my mats a little on the thin side. I don't mind practicing on a bare floor, and I think thin mats get me the closest approximation to practicing on "the ground with stick". When I attended a Noah Maze workshop early this year I noticed he rolled out a mat that at first almost looked like a long black piece of paper. I don't even know where you
get such a mat. It was crazy looking, but he prefers the thinnest mat possible.
This is all personal preference, but the point is that it IS an entirely individual situation. Your mat supports and holds you through the long journey of your practice. It needs to fit you, your practice, and your needs. Thick may not be it, so remember that when shopping for your next mat. Listen to your body, not to popular opinion.