How should I use my potential Rosetta Stone subscription?

P.S.: If you make a suggestion for a different language, please let me know how easy it would be to learn; if I could become pretty much fluent in something within six months I'd be more likely to pursue that than something with lower practical returns (yes I know Arabic is a very challenging language).

I can't speak for much of this question but I've attempted Rosetta Stone for Arabic and I think it would not be a good starting place for a total beginner. I can already read and write Arabic so I skipped to the oral parts, which I didn't get very far into because it irritated me due to being completely in really formal Modern Standard Arabic. It uses case endings, which are not spoken except in very formal contexts, like religious recitation, and doesn't do a good job at all of explaining why they are there (if I remember correctly it doesn't tell you at all, so you would be learning words with additional vowel sounds at the end without fully understanding what they are there for--I might have skipped over quite a bit of the introductory stuff, however). In your position I would probably just pick up the Spanish (Latin American) version and begin Arabic with an actual teacher--sorry to be boring! Maybe you could pick up Portuguese if you want something different from Spanish that would still be close enough to where the Rosetta Stone could help you? Just a suggestion.

My son learned Arabic-one thing he found out is that what is taught is standard Arabic but the truth is there are many dialects of Arabic -so a lot depends on what you actually would want to do with it. I think I'd go with the Spanish myself.

I did take Arabic for about two months in college so I have a VERY VERY basic knowledge; I know about case endings and that there are many dialects. I used to know the alphabet and some basic phrases but it's been years. I don't know the actual language but I have a decent amount of knowledge ABOUT the language.

I'd stick with Spanish for two reasons. First, it's easier and you know more already so it's going to be less frustrating (at least, I would find it less frustrating), which means you're probably more likely to stick with it. Second, as you found out, when you don't use a language for a long time, you start forgetting. You're going to have a lot more opportunities to practice/use Spanish in daily life than Arabic.

Spanish is the obvious answer if you want this to be practical. But if you don't really care about being practical and just want to do something fun, I would recommend Turkish. Turkish is actually quite a simple language to pick up, despite its relative distance from English. I personally find the sound of it to be very pleasant due to the vowel harmony. It's written phonetically and in Latin script, so it's very easy to sound out words as you read them (this might be a stumbling block with Arabic). I spent about a month learning Turkish out of a book before I went on a trip there a couple years ago, and I could get surprisingly far with what I had learned in that short time. Turkey is a fantastic place to visit as well, although right now might not be such a good time... There are also many Turkish expats living in the US if you wanted to practice.

I'm going to throw Russian out there for consideration. Lots of former USSR countries still use the language, lots of Russian speaking enclaves in the Northeast, and its a different language family so it'll mush your brain around more to learn it. I'd also consider Mandarin, or something totally foreign just to see what it's like.

Spanish because 1) Rosetta Stone Spanish is OK, 2) you have a foundation in it, 3) because it's very useful in the US, and 4) because it's a lot easier than Arabic (do you really want to deal with 12 verb conjugations or whatever it is with Arabic?). So with Spanish you will actually be able to achieve something that you will actually be able to use and will give you a sense of accomplishment. With Rosetta Stone you can also use the mobile app, which is great because you can squeeze in a little practice every time you have a spare 10 or 15 minutes here and there throughout the day and evening. And you can supplement it with Duolingo, which is free and similar.

I too got RS free from my employer. I was not impressed. It might be okay as a refresher for a language you already know but I would not use it to learn a new one. So, um, Spanish?