Thanks for the encouragement.HF SSB is alive & well. In general, the most "interesting" non-ham SSB doesn't last very long (like mere seconds). The less interesting, the longer it runs.
Aircraft LDOC (flying over ocean regions) can readily be found - but in general isn't exciting until some plane has a problem of some sort. English is the common language for aviation communications everywhere (almost).
Depending on how many languages you are proficient in, the more interesting voice SSB transmissions you might be able to log.
A spectrum / waterfall display is of great help in catching active frequencies. You get that with any SDR.
Frequencies? Try any range between a ham band and an 'international broadcast' band, e.g. 7.5 - 9 MHz. Or you could narrow your search by looking into one service at a time.
Be patient. You'll find interesting stuff.