I find it really hard to find sheer "full coverage" panties in SL. By "full coverage" I mean ones that cover your bottom. Not thongs, tangas, g-strings. By sheer I mean see-through. Lace and mesh are common types of see-through fabric.
Matching sheer bras would be a plus factor.
Here's one example of one type of the sort of thing I mean:
http://www.barenecessities.com/productViews.aspx?Image_cat_id=1&pf_id=Wacoal843148
I'm not just looking for that specific item, or just for things extremely similar to that. They could be mesh, polka-dot mesh, any of a variety of lace patterns, string bikinis that cover your butt, hipsters, low-rise, high-rise, etc.