http://www.rei.com/product/827995/rei-tranquility-shoulder-bag-womens I'm torn by hearing mixed reviews. My husband seemed to like the look of the Baggallini but I'm hearing negatives about the straps slipping and space issues? With the Overland Donner, I'm not sure how comfortable it is to carry. Any insight? I like the look of the REI Tranquility bag in the link, but I can't find a review on it. Does anyone have experience with it or can anyone sell me on one over the other? I'll be toting for me, my husband and 2 small kids. 5 and 2.