55 days left - Taking Veritas Prep - Which other resource to combine?

Glad to hear that your class is going well, David! And since you're obviously doing your homework on finding good supplemental resources I'm sure you're keeping up with class homework, too, which helps quite a bit!

My take on your situation: I'd focus your efforts on finding more PRACTICE as opposed to finding more strategy. Let your class and its resources provide the strategy, and then use additional resources (like the Official Guide series) to sharpen and repeat that strategy.

So I'd prioritize the Official Guide series, and actually (not to complicate things) I'd also (and maybe more emphatically) recommend:

-The GMAT Prep Question Pack (https://www.mba.com/us/store/store-catalog/gmat-preparation/gmatprep-question-pack-1.aspx)
-The GMAT Focus quant diagnostic software (https://www.mba.com/us/store/store-catalog/gmat-preparation/gmat-focus-online-quantitative-diagnostic-tool.aspx)

What I like about those:

1) They're newer, so they contain newer* problems, which helps to get the most current feel for what you'll see on test day (*note - not all problems are brand new, but the newer resources tend to mix in newer problems as a general rule)
2) They're online, so they get you used to seeing questions on a computer screen like you will on test day
3) With the Quant Focus, it's adaptive so it has to have harder questions in it (to adapt to a higher ability level) and will challenge you with problems like you'll see on test day, in your ability range.