Writing between a man and woman is slightly easier for me since the social issues with both are near equivalent in the Star Wars universe, possibly even ancient compared to modern, western society based on the type of Star Wars culture since it's biological (difference in muscle mass, dealing with pregnancy and periods) and Star Wars does display typical gender roles of real life (and subverts them too). So, it's interesting to me to write either sex since I identity with one and can make interesting character traits with the other.
Differences in race is more cultural, and it seems that humanity is pretty tolerant of other human races by default in Star Wars. Alderaan is possibly the closest thing to having a majority group of similar non-white skin tone on a single planet, yet they apparently can accept a totally white princess from a non-white couple (or just assumed it was adultery, who knows?). Plus, we now have a black storm trooper and I sincerely doubt his race will bring new social commentary about the Star Wars universe (or maybe it will, who knows?). It's less interesting to me to write a character for the sake of being another race, since I'd feel like I'd be writing a white person with a non-white avatar and thus cannot build character ticks from that. If I saw a picture or playby that really interested me or gave me a good character idea, I'd probably roll with a non-white. This was probably exactly how John Boyega got the leading role - he just looked and acted like he would make the character come to life.
Non-humans are more interesting in that regard, then, yet I'm not one to make a bunch of characters and haven't gotten around to actively roleplaying one on Star Wars Chaos. I've at least tried several times before, though.