My Scions of Nathas saga used language barriers extensively. Although this was critical in my heavily non-canon world.
The PCs arrived on a new world and immediately began interacting with the locals with whom they shared no languages (except for the drakes but thats another story for another time). They rapidly adopted mentem effects to ease communication and many of the races are magically powerful and had their own translation effects and items, although typically only available to people like high nobles, monarchs and ambassadors (i.e. people who might reasonably require translation).
We are now 18 years into the saga and most of the PCs speak three or four languages
Nassain - the native language of their home, used for everyday stuff and for academics
Draconic or Olympian - the two magical tongues, one for mages and druids and the other for priests and paladins. i.e. generally the casters know only one of these, only really used for casting and for worship, often used to speak to each other without others listening in
Elven - First civilized race the PCs met, they needed this to be able to read the books and such like they found in the ruins near where they live
Dwarven - Powerful race to the north who the players have become somewhat close to.
Languages they don't know but have a skilled translator trained up for:
Lizard - an ancient and faded but still freakishly magical race to the south, not speakable by humans due to lack of teeth
Minotaur - A friendly and agrarian culture to the south, humans sound stupid speaking this but can make themselves understood
Languages they don't have a clue on:
LGMotF - Little Green Men of the Forest - essentially goblins. Some tribes are friendly and gregarious, some homicidal and sadistic, most fall some where in the middle. LGMotF caravans often swing through the players lands to trade. A basic pidgin, gestures and when required magic, are used to converse.
Fishmen - Foul and vicious brutes, they have a recognisable language but prefer to eat people than talk to them.
Orcish - There are two races of orcs, one that fits all the stereotypes and one that is smarter (if a little smaller) and has really got its shit together. Both speak the same language, although the smart ones use Elven for magical purposes too.
Most of the players have sunk a lot of xp into learning languages but have been helped by their scholars, who they send off to live with ammenable locals to learn the language. These scholars then teach it individually to interested PCs. Since most have a positive com score and a few points in teaching (most were professors, teachers and scholars before the saga started), PCs can reasonably expect 13-15 xp per season of study. The best scholar for this (who has good teacher) teaches around 18xp a season which is enough to get a score of 5 in a language in less than a year (with a bit of adventure xp thrown in). Most players get the language to 4 (to be able to read it) and stop there. A few go to five and one has Elven at 6 and hence speaks it better than most Elves.
We have had real fun with languages. Those wonderful moments when they enocunter a new race and struggle to get across "Please don't kill me, I am not an enemy". Also fun when the party splits and something happens and a local is trying to convey something terribly important, when both players remind me that actually, they don't speak the language and have no idea what the guy is babbling about.