I am disappointed, this thread is not nearly as controversial as expected. Maybe I can help, I personally reject the position that you are free to dress as whim dictates without incurring some retribution. After many years of being a free-spirit, it pains me to say that clothes really are a reflection of you, and more importantly a show of respect for others. (I can see the smug smirk on my Mother's face now!) As a clear example, to stroll into St.Peters wearing short-shorts, tank top, and flip flops makes you look foolish and insults those who view the church as a sacred place...justifying any action taken by the Swiss Guard (and yes, they carry sub-machine guns, not just pikes). All that said, what should you consider when packing?
---Space/Weight: Jeans are versatile, but heavy, shorts are OK but not appropriate for all (many) situations, your goal is to find 2 to 3 outfits that basically work in all situations (Comfortable sightseeing, a nice dinner, visiting a church, etc.) Same with shoes, a nuetral pair of leather oxfords in a walking shoe are super versatile, carrying my dress shoes, a pair of tennis shoes (white or otherwise), a pair of sandals, and a pair of hiking boots is silly.
---Color coordination: Nuetrals are great because of your few outfits, everything can be mixed and matched. The further I deviate from nuetral...the more items I need to have the same versatility.
---Availability: I actually pack lighter than needed, with the expectation that I will probably pick up a shirt along the way, maybe some accessory, who knows.
Overall, taking this tact, I guess I might "blend" more, though not intended, but I probably do attract less attention. For those who debate the "security Issue" with dress, I guess I can only ask "What will a thief scanning a crowd in a piazza pick up on first?" and view as a "richer" target. a non-descript individual? or the Clark Griswalds of the world?