Describe someone who is a specific type of annoying

(sorry for bad title, will accept edit of better one)

There's a specific type of person who my friends and I find annoying, but we don't know the word(s) to describe them.

The closest I can get to:
It's that feeling that you get around someone who goes on and on about their "trip to Cambodia" (or wherever), and about "how impactful it was", and about how "we should all try to live more simple lives, man".

Most sitcoms have had an episode where this character/trope occurs (The yak in Zootopia, for example).

It's kind of like "social justice warrior", but that's not quite right either. Does anyone have the term for this person?

My working terms (made up, obviously):

• Round-trip philosopher
• Socialist hipster
• Sarah McLaughlin sympathizer (a joke)

Sanctimonious

A good adjective to use might be sanctimonious:

• pretending to be morally better than other people

  _{-- Merriam-Webster}

• [derogatory] Making a show of being morally superior to other people.

  _{-- Oxford Dictionaries}

Perhaps a good phrase to describe the kind of person you're talking about would be a sanctimonius traveller?

Ostentatious

My first thought when I saw the question was ostentatious:

• displaying wealth, knowledge, etc., in a way that is meant to attract attention, admiration, or envy

• marked by or fond of conspicuous or vainglorious and sometimes pretentious display

                  — Merriam-Webster