Heather, we actually have 2 lockers. One holds our mini Keurig, too :good vibes
In addition to personal items, I have rain jackets, umbrellas, walking sticks, a backpack, flip flops, extra tennis shoes, Sun tan/burn supplies, a tide to go stick. First aid with basics items; band aids, benedryl, neosporin, analgesics, bee sting stick, toe nail and finger nail clippers. A hair brush. We have coffee cups and tall plastic glasses. Also old refillable mugs to carry to the pool with our refreshment of the day. I keep extra pins for trading, detergent for the washing machine, Florida map, our Hidden Mickey book, a carry blanket to take with us on cold nights - usually for the Candlelight Processional. Some clothing and a small tool kit with a leatherman. Hats and/or visor. I even have a deck of cards though haven't used them in nearly a decade. Clorox wipes and a larger size Purell to fill my purse size one.
I'm sure there's more, off the top of my head, this is what I can think of.
I don't keep a Brita though I know that many people do. With just the 2 of us, I'll order 1 or 2 cases of water from Cosco and have it delivered directly to the Lodge. If we run out, I'll buy the gallon - that isn't too expensive by Disney standards - from the Mercantile.
Have fun getting all your things together! I went to our local
WalMart and purchased small plastic boxes in various sizes with lids that are stackable. It's worked out pretty well for us. We each have one of the larger ones for our personal items. My k-cups are in another. Pins in yet another.