Welcome Magz to a very helpful and fun-loving board!!
Helpful: Your question is one that is almost impossible to answer because it is such a personal decision and there are so many different styles from classy, to sporty to flat out bling. There is a thread that was started where others will help you with photochops, so if you have pics of your car and some pics of wheels you know you like try posting there to get a sneak preview of whether or not you will like the end result.
Fun-loving: Instead of rims, why not splurge and go for the whole wheel... and the AWD is already so tall, I worry that 20 foot wheels might be a little over the top. You might consider 20" wheels however!
Sorry Magz, couldn't resist... all in good fun! Good luck with your decision-making and be sure to post some pics of your car... before and after.