I adore yoga bags. In fact I have about 10 of them which I used to trade up per season. They make carrying your mat around much, much easier. Especially if they have an adjustable shoulder strap.
I have a pvc free mat that I use all the time. The trouble with the thicker mats is you do have to find a bag that fits it.
Many times the thicker mats will get stuck and will not slide down into the bag. Or if you get it into the bag it may be too long to squeeze it in so it won’t close.
Some bags offer a little zipper pouch that allow you to carry other things with you.
They truly are a matter of preference.
Some tips when choosing a bag:
1) Find one that is aesthetically pleasing; it will make you want to carry it and therefore encourage you to GO to class!
2) Be sure you know the dimensions of the bag so you aren’t disappointed if you’re mat won’t fit.
3) You may have to spend a bit more money to find a good quality bag so it doesn’t fall apart.
4) I’d suggest finding one with an adjustable shoulder strap so you can be comfortable while carrying it around.
5) Consider if you wish to have spots on your bag for additional storage; do you want it to hold your water bottle, keys, membership cards?
Remember to wash your bag occassionally and hang it to dry to so it won’t shrink on you.