Labeling

This past week or so, a few of the blogs I follow have been talking about labeling clothing.  Now, I have embroidered labels that I'll use up before I start making my own, but the idea of putting sizes in garments sounds like a fantastic idea to me but...  What do you do about the difference between RTW sizing and pattern sizing?  We all know that it's different.  For example, Gracie is currently in 5T for length.  It's still a bit too wide on her, but she needs the extra size in most cases so that her tummy isn't hanging out.  But in pattern sizes, she's a 3 in both toddler and child patterns.  So which size do I put on her Aunt-Laura-Made-It clothing?  Any opinions?