The blending of cotton and silk creates a great charkha fiber.  With the exception of the
Angel Wings blend, the silk adds sheen and strength to the cotton in these blends.  
Another item to note if you are interested in spinning cotton and silk is that silk will
take acid dyes (I have learned by experience that cotton does not), so dying these
blends with acid dyes may create an interesting effect.
This blend is 30% cotton,
30% silk.  The silk is
Bombyx, and this blend does
take on some of the spinning
characteristics of the bombyx
silk, so if you are used to
spinning cotton, spinning this
blend may take some getting
used to.
This blend is cotton with silk noils,
which is short, nubby bits of silk that
add the texture to this blend.  These
nubs actually make the blend as a whole
weaker than the cotton by itself,
making it somewhat difficult to spin.  I
would not recommend this blend to a
beginner, but it has a neat texture
creating a chenille-like yarn.
I like any blend that adds naturally
colored cotton.  With this blend,
brown cotton is added to silk.  I
suspect the silk in this case is tussah
silk, because its natural color would
add interest to this blend, plus this
blend was somewhat easier to spin
than with the 70/30 cotton silk blend.
 Of the three blends on this page, this
is probably the best blend for a
beginner.
Cotton/Silk Blends