Boulders and a Backpack work for me.
I currently have (9) 100 cards deck boxes, (1) 60 card deck box for tokens, (1) bag of dice, a trade binder, and a playmat in this bag. I haven't even used the big top pocket yet, so I can easily hold more decks. Every spot holding a 100 card deckbox can also hold a 60 card deckbox in front of it.
I bring most my decks just because I like to be able to sit down at any table. Sometimes I get to use my strongest decks, sometimes I need something a little nicer to use with the new guys at the LGS. Being able to scale up or down on the power level to match the table is nice. They are also all stored in the bag anyways, it would be harder for me not to bring them all.
I currently have 12 boulder deck boxes in the bottom part, another one in the top pocket along with my dice bag, a trade binder in the laptop slot , and I use the tripod spot for my playmat.