Over the past few years, I've purchased both the Seacamp II and Newport H2 for my daughter (now 9 yo). I like both, but the Seacamp is much lighter, and I believe, more comfortable. I love these shoes and buy a new pair for her every summer. They dry quickly and wash easily, and DD wears almost every day at summer day camp. When we were at WDW 1 1/2 years ago, the Seacamps were worn at the parks every day, but I had her switch into different shoes at the resort and a few times for dinners just to give her feet a break. By the way, I take DD to a local sporting goods store to try on for sizing, but then order from Amazon, as I found a big difference in pricing. I bought my Keen Whispers and DH's Keen Newport (leather) via Amazon, as well.
Sandal wise, my wife and I both have used the Newport H2s for ages and many times at Disney. Shoes; I've used the Targhee/Targhee II as my daily wear for a few years now. I've also traveled with both the Targhees and the Newports and walked a lot with both. Both have worked great for us!
Newports! My kids and I have 12 pairs, between the four of us (my husband is resisting). We walk all over the city (and Disney) in ours, sometimes 5-7 miles a day. You will not regret joining the Keen side.
It just so happens that last night, we did a test at my house to decide which pair to keep and which pair to send back to Zappos. I have an 8 y.o. girl who is picky about what is on her feet. She has always had the Newport H2 and loved it, but this year she saw Seacamp with snazzier colors and stripes and wanted to give it a try. She tried both pairs in size 2. OPs are correct--Seacamp is lighter weight. But after wearing one of each around the house for the whole afternoon/evening, my 8 y.o. chose the Newport H2, declaring it "more comfortable, but not as cute." According to her (I have never tried Keens), the Velcro makes it easier to adjust the tightness of the foot opening and the little plastic toggle thing rests on the top of the Velcro rather than digging into your foot if you cinch them up tight. My advice is....Zappos. Try a few. Return what doesn't work. I love Zappos. And I'm not being paid to say that.
Some outdoor sporting stores carry them like REI. Nordstrom carries the kids sizes. I think it is best to find someplace online that has free shipping and free returns and order several different styles and just send back the ones that don't work. As I posted on another thread: if you wear a women's size 8 or smaller, go for the kids sizes for half the price (a kids 5 is around a women's 7 and a kids 6 is around a women's 8).