Relaxation interrupted

I've been regularly attending a yoga class on Thursday nights since October. It has helped with my flexibility and strength, but it's also helped me keep everyday annoyances in perspective, such as work frustrations or trying to figure out what to make for dinner once I get home. I'm not naturally gifted at relaxation/meditation, but I'm getting better at it by practicing.
Ironically, while I can keep outside annoyances in check during yoga class, I cannot GET OVER how annoying some people are in yoga class. Here are a few examples:

Our class begins at 6:30 p.m. I tend to arrive at the gym a little before 6:00 p.m. and I place my mat in my favorite spot (back interior corner, no drafts!) and then warm up on the elliptical machine. I arrive in the yoga "studio" at 6:25 to get ready for class. Last week there were only 3 people there at 6:25. Tonight there were 15 people there. Three more straggled in before 6:30, creating quite a packed house. Our instructor turned down the lights and began the class. At 6:50 (yes, I looked at the clock) one woman walked in, picked up a mat, walked around the entire room trying to find a spot, and then "nestled" herself in between four of us who were there from the get-go, forcing us to re-arrange our mats because otherwise we'd be knocking arms with each other during the sun salutations. And then she kept moving her stuff around: her blanket ended up at the top of my mat and I was about to throw it at her. Another woman arrived at 6:55 and at least she had the good sense to pick a corner spot near the door. Being that I have an (overabundant) sense of justice, I was incensed that this late arrival thought she had the right to disrupt four of us who had arrived on time and were 20 minutes into the class when she arrived. I admit, it took me about 10 minutes to stop fuming. After that, I just got annoyed every time I had to move to accomodate her. Do you think that a gym should have a policy against people entering yoga classes that have been in session more than 10 minutes?

And I won't even discuss the inappropriate undergarments (or lack thereof) I have the misfortune of seeing during class. Don't people understand that we're going to be doing a lot of stetching and bending in yoga class and that they should pick clothing that allows them freedom of movement without flashing the crack of their behind to those of us unfortunate enough to be stationed behind them? Sigh.

I can usually pull it back together enough to enjoy the ending relaxation, but I admit that these things annoy me, right in the middle of me trying to relax. I guess I have a lot of yoga learning still to do.