Here's a link to Assimil. You can find the book + the audio easily on torrents. And I think you should read the reviews on amazon, and generally reviews about assimil about what makes it so great. They probably word it better than I do, however even though assimil claims to take you to B1, I think A2 level is more likely, and after finishing the book, you can immediately continue with their advanced book which should take you above B1 called "Assimil Using French".
Is this the Assimil you are referring to? I've noticed there are a lot of different versions.
> I'd like to learn French this year, but I have less time to commit than I have in previous years. Is it possible to work language learning into a situation where you're short on time?
Most definitely. What matters most is consistency. Coincidentally, this is one of my favourite language courses ever, for French. The Assimil method in particular is built upon the "day-to-day method", meaning you work on one lesson a day, for 15 minutes to an hour. If you do that for a few months (I believe that course is 115 lessons), your French will be WELL on it's way. There's more to the Assimil method in particular, but that is mostly covered in the Amazon reviews if you're curious.
> Also, how do you feel about high school/college language courses?
They can be great with an enthusiastic teacher. But students in general don't tend to care about them enough, and as a result learn nothing.
I don't believe that you truly learned French. Start anew. This time around, make sure that you can actually "speak" French. Focus more on speaking, instead of passive listening comprehension.
As for the "best" way, I believe Assimil French with Ease is a very popular course. I am not sure if it's "best", whatever that means, for you. You will have to find out what works "best" for you.