Which is the preferred expression in the Rhine/Mosel areas? I learned to use it in the Italian Dolomites and Bavaria. Such a nice phrase, but I'd like to be appropriate. Is there a German equivalent for "hi" or is "hallo" the common term?
Say "Hallo". "Grüß Gott" is only for southern Bavaria and some parts of Austria. "Guten Tag" is rather formal.
I think in the Rhein/Mosel region I most likely hear "Guten Tag" (good day). It's in Catholic Bavaria, in particular southern Bavaria, that I hear Grüß Gott (God's greeting). In the 1980s I stayed in Heidelberg, Rothenburg, and even in Munich, without hearing anyone use Grüß Gott. It wasn't until I got to Garmisch-Partenkirchen that I first heard the term. I think today it is more widely used in Bavaria, like in Munich.
Just listen to what they use and follow suit. If you enter a store and the clerk greets you with "Tag", say Tag back, but if they say Grüß Gott, return it.
You can say whatever you prefer, even in Bavaria you can say Guten Tag, or in the morning, Guten Morgen. You don't hear Grüß Gott up north, but if you like saying it, people will be ok and understand what you mean. All Germans know that this is a Bavarian greeting. You may hear a lot of Moin, Moin as a greeting throughout the day. It is more prevalent up north, but also popular in other parts of Germany. I hear it a lot in Frankfurt.
Also, the German "Hallo" should be pronounced with definite "a" vowel sound as in "pal", not like "Hello".
Walking through the hotel in the mornings most people I've ever spoken with just say "Morgen" in passing.
Rule of thumb: "Grüß Gott" only in Southern Bavaria, all over Austria and in Alto Adige (Südtirol). NOT in Switzerland.
Grüß Gott is also appropriate in the Schwabian region (around Stuttgart).
As Andreas noted, it is not to be confused with the Swiss greeting Grüezi (or Grüezi mitenand for more than one person).
As pointed out to you, say "Grüß Gott" in Austria or "Servus" in Vienna, Grüß Gott in Bavaria. In the middle Rhine area Guten Tag is fine or, more informally, just say "Tag" to shorten it. To say "bye" as when you leave the store, say Tschüss or Wiedersehen...good enough.
What fun! All sorts of ways to greet people - but not "Grüß Gott" where we're headed. I appreciate knowing the more colloquial greetings. I learned some new ones (Tschüss and Moin). We truly heard and said "Grüß Gott" a lot in the Alto Adige (Südtirol) and Bavaria. Thanks, everyone!