In this case "travels" is likely correct, and possibly more so than the singular version. The implication is that the person being addressed is (or will be) engaged is some sort of extended traveling (method does not matter) and hence more than one "travel". For the case of a simple trip, however, "Have a safe trip" would be more idiomatic. And note that using the plural of "travel" is ...
I believe you should use Travels for your root folder name. The folder is a photographic chronicle of your travels, as you would say, and the pluralization reflects the further division into different locations. I think this would be more correct than calling the folder travel, although travel could also work if you looked at the collection of pictures as a single entity.
I suspect "globetrotter" might fit, even though the provided definition "a person who travels widely" doesn't specifically call out air travel. The set of people who are likely to be called "globetrotters" who do not travel by air on a regular basis is likely vanishingly small.
Peri- is the Greek word for "around," and peripatetic is an adjective that describes someone who likes to walk or travel around. Peripatetic is also a noun for a person who travels from one place to another or moves around a lot. SO.. Peripatetic If someone has a peripatetic life or career, they travel around a lot, living or working in places for short periods of time. _Collins ...works here.
However, if Doctor Who (or any other time traveler) travels in time he doesn't qualify. Although if his TARDIS malfunctioned and he ended up stranded in a parallel universe, you could argue that he qualifies for that title. So the question is: is there a colloquial term to call those characters in English?