I'm a fan of the Ross chain over Marshall's or similar stores. With stores of this type, it's always going to be hit and miss on any given day. On my most recent visit, this location had a really good sized dress section which worked out well since dresses were at the top of my list. However, when I went to look for jeans, there were literally less than 10 pairs on the rack.
There is a decent number of fitting rooms and they're plenty roomy. The ladies who were manning the fitting rooms that day were very helpful with holding on to items I wanted to keep so they didn't count toward the garments I was taking in with me.
I always check out the shoe section at these types of shops because they have a 10+ section and you never know when you're going to get lucky. Sadly, 9 out of 10 times, you're left with slim pickings. That's just how it goes with 10+ sizes for women.