I did one of this pattern for a friends baby and now everyone wants one... lol..
I keep using up what I consider the 'perfect' field fabric and have to go on the hunt for something else that will work... that one always seems to become the 'perfect' fabric... until I use THAT one up.... heh... so many options.
I did find one that I try to use on all of mine... I bought several yards in order to have it for this pattern specifically. It is a green(ish) fabric with gold dragon flies on it... it is PERFECT for the band separating what I consider the 'pond' (where the DF's are) and the 'field' (that the pond sits in).
I love your choice of the purple... i have stayed with blues and greens so far, but that is absolutely striking.