Joined: Aug 2010
Posts: 12,728
Likes: 2,106
From: Madison, WI
Bikes: 1961 Ideor, 1966 Perfekt 3 Speed AB Hub, 1994 Bridgestone MB-6, 2006 Airnimal Joey, 2009 Thorn Sherpa, 2013 Thorn Nomad MkII, 2015 VO Pass Hunter, 2017 Lynskey Backroad, 2017 Raleigh Gran Prix, 1980s Bianchi Mixte on a trainer. Others are now gone.
For what you are doing, I assume you do not go if it looks like rainy or bad weather.
When I put on a pannier to haul stuff during the day when I will be back home later that day, I just use shopping type panniers. The kind that are open on top and shaped like a grocery bag. But if you wanted to have the top close, you could put a big stuff sack or dry bag or day pack in the shopping pannier. And shopping panniers come in handy if you want to go ... shopping, making them a dual purpose item. Since it sounds like you would be digging into them several times each day, they might make more sense than a touring type pannier that is designed more for rugged travel, less for ease of access.
Shopping panniers are usually sold as singles.
I have several touring type panniers, but I use them for touring, not day trips.