When I traveled for 3 weeks last year I took 6 64gb cards and also backed them up every night onto my laptop so I had two copies. I like having multiple copies so I would go with the larger cards.
When shooting RAW 32-64GB is the sweet spot for me. Less than that and I have to carry multiple cards at a time. Obviously, the volume you shoot and the size of your files may dictate a different size for you.