I see so many girls carrying the large cotton duffel bags at train stations and in airports. How handy are they? Is it safe to check them, or should I carry it on? I'm thinking of getting one for my upcoming trip to Alaska in July. Does anyone recommend them? Here is a picture of the bag: http://www.verabradley.com/Site/Store/ProductDetail.aspx?sku=341%3a41& TIA!