I have been wrestling with this topic for years. I think I have made some spiritual progress in growth along the way, but I am amazed at how slowly my understanding and successful implementation of Biblical principles on this matter has been.
I certainly think it can be over-simplified into a discussion about how much is too much, what is necessity and luxury, but that quickly becomes a discussion about rules or opinions and boundaries (legalism) and stops being about why one should approach life, Biblically with simplicity.
Tomorrow I have to go deeper and preach on the topic at church. Link through here mid next week and the mp3 should be there for a listen if you are interested.
I think it will be an interesting time of reflection.