As someone who works in a shoe store, from my own experience and the experience of my customers, I hear different things about certain brands, but all of them are in the range of what would be considered 'comfort' brands.
I, however, find that J41's are more comfortable in their slip-ons as opposed to their sandals, but I haven't tried too many of the sandals on. It's just that their straps are so dainty and thin that it unnerves me, but that's just my silly irrational concern. I haven't heard anything terrible about the J-41 strappy sandals so I'm assuming they're just fine. Something more like
this would stay on better. They do fit a little more snuggly, so go a half-size to a size up depending on your foot.
Keen and Teva sandals I will both recommend as they are our most comfortable and popular walking sandal brands. I'll also throw in a Clarks Privo recommendation. This one
here is going to be rather comfortable as the insole technology is going to give you arch support you're looking for and a soft, cushiony bed to absorb the force of your weight as it comes down through your feet and into the insole, but Keen and Teva do the same thing.
Really any of those brands are going to work well for what you're looking for. It's just a matter of going to a place that has most if not all these brands and trying them on (ahem, DSW is usually one of them, if you have a location nearby (since your username says you're in Oregon, there are locations in Portland at Cascade Station, Hillsboro at Tanasbourne Village, and in Tigard at Bridgeport Village. There is one in Eugene, too, but I dunno where you are!) I suggest calling ahead to ask if they have these three brands.
Good luck! I know I'll probably invest in some J-41's myself soon before I go in August.