Fly and walk in sneakers. Coordinate your clothes to use the same color shoes. I usually choose black or navy. I bring a pair of slides, closed toe flats and a pair of heels all in the same color. Never ever bring new shoes. Always bring well broken-in shoes that are extremely comfortable. I insist on comfort. Just in case, bring moleskin for those blisters if you get them. If you plan on using the pool a lot, the slides are great for the pool and also go well with casual clothes in warm places. If you are not a pool person or are going to a cool climate, leave the slides home. And if you forget something and need it, it's a great excuse to shop. On a Baltic cruise a few years ago, I thought it would be cold so I left home my slides. It was a great excuse to buy a pair of ECCO sandals in Denmark. Got them real cheap and have enjoyed using them. It was not only fun to buy, it also is a very useful souvenir. Also, I put the black flats in my carryon. If your suitcase is lost (mine was lost last year for a week) I still was able to function very well with just sneakers and flats.