Anything that is marked USB-C PD (or, Power Delivery) will work very well with the S8+. Also, anything that is marked QC, QC 3.0 or Qualcomm Quickcharge will work brilliantly with the S8+. These product will allow you to rapidly charge your phone just as the power adapter you received out of the box would do. Any of the Anker PowerCore devices will serve you well, just find a charging capacity that fits your needs/budget.
Also, I would recommend, since you'll be traveling, that you pick up a pair of bluetooth earbuds if you do not have any you like already. I use the Anker SoundBuds Sport and I love them!