For the longest time, I didnt really even realize that you could use antialiasing='true' in your layer renderers. Of course, I had always used this when doing any type of labeling, but never in layer renderers. It works exceptionally well in some cases and not much of a difference in others. Using it looks very nice when doing line features, such as streets.
This is the typical way that I render my street layers and it looks so much better when using antialiasing:
<SIMPLELINESYMBOL width="4" antialiasing="true" captype="round" color="192,126,61" />
<SIMPLELINESYMBOL width="2" antialiasing="true" captype="round" color="255,255,255" />