A LOT of beginning shooters have difficulty in making interesting, impactful pictures with really wide-angle lenses. The issue is the temptation to zoom alllll the way out to the short end, and then to take a shot from not-anywhere-near-close-enough. This leads to pictures with distant-looking background stuff, rendered small, and low in detail, and lacking in visual interest.
It takes a lot of dedicated practice to learn how best to use a very wide-angle zoom lens. Lower focal length usually means lower interest, in anything beyond 10 or 15 feet distant. I honestly think that, for many places, TELE-landscape and telephoto travel shots can have more interest, reveal more detail, and also, create more-pleasing pictures than wide-angle shots.
24 to 85mm on FF is a great walkaround lens. So, with the current lens lineup having the 18-135, plus the 50mm f/1.4 Canon which is a very solid lens, I honestly think that the 55-250 STM might be the handier, better lens for travel use. You might ALSO consider the new 24 and 40mm pancake primes Canon offers! SMALL, easy-to-carry in a waist pack, sharp, f/2.8, $199 each more or less.