Slovenia does not usually come top of mind when thinking about Mediterranean destinations. And this is precisely what makes it such a great pick. It has great seaside hotels like the Palace; fine restaurants; and a relaxed, laid back atmosphere that comes from a primarily local tourism industry. Portoroz is a small town, with charming architecture which reflects influences from its neighboring Austria and Italy. It seems that Slovenians have been very smart about taking the best of each. They take great pride in the appearance of their town and you will find that it is a spotless, pristine little location. Furthermore, you will have absolutely no problem communicating. It is very common for the average Slovenian to speak no less than 5 languages! The roads neighboring Portoroz are in very good condition which means you have several options to fly in or drive. While there is a Portoroz airport, it offers limited flights. The preferred option is usually Trieste which brings in primarily Italian youth, looking to have a fun week-end in the nearby casinos. (Even though Trieste is of course in Italy, the drive to Portoroz is less than an hour).
If you have a bit more time in Slovenia, another charming location is Bled by the Lake. Its view of the iconic castle perched on the mountain by the lake, make it a popular tourist destination as well. If flying into Bled you have the option of flying into Trieste or Lubljana.