First of all, we have no idea how many shots you're planning on taking. Are you going on a photo adventure and going to shoot a lot of photos, or just a casual vacation and will take a few shots to record your trip. In addition, are you going to have access to a battery charger during the trip, and are you taking a computer and/or hard drive do load your photos on as the memory cards get filled up?
As far as what size of SD to get, I can only tell you what I would now purchase which is either 32 or 64 GB cards; how many you need is another question. I tend to use either the Sandisk or Lexar brands, and look for a minimum speed of about 90-100 mb/sec, but those are likely faster than my camera can write to the card. Whatever size you get, make sure that they are not micro SD cards with an adaptor, which might not really fit your camera. I'd look at online camera stores such as Adorama or B&H Photo for these to get an idea of how much they cost at the time, but they are relatively inexpensive.
Let us know.
WM