In the noble spirit of one immortal oratorm when he so colorfully advised our hero . . .

This business is well ended.
My liege, and madam, to expostulate
What majesty should be, what duty is,
Why day is day, night night, and time is time,
Were nothing but to waste night, day and time.
Therefore, since brevity is the soul of wit,
And tediousness the limbs and outward flourishes,
I will be brief: your noble son is mad:
Mad call I it; for, to define true madness,
What is’t but to be nothing else but mad?
But let that go.

. . . I can myself do little less than recommend vigorously not timorously, for timor no more profits a man than it does a mouse or a moth, any of the following fine and splendid formulations of art:

• chatty
• circuitous
• circumlocutory
• desultory
• diffuse
• digressive
• discursive
• evasive
• gabby
• garrulous
• long-winded
• loquacious
• maundering
• meandering
• palaverous
• prolix
• rambling
• talkative
• turgid
• vague
• verbose
• waffling
• windy
• wordy

and of course, my personal favorite word for vexing prattlers wont to sacrifice wit’s soul on the altar of florid flourish:

•  Polonian

If you are actually talking about someone who waffles on long-windedly before getting to the point (rather than someone who doesn’t say things straight out and honestly, which is how I too would understand ‘straight talk’), the first idiom that comes to mind is beating around the bush.

I'd suggest pussyfoot for the specific use you mentioned. In other uses, I might say an antonym for straight talk would be euphemism or the vulgar B.S. even.

The opposite of straight is crooked (the adjective /'krʊkəd/, not the past participle /krʊkt/).

The opposite of talking is thinking, in the sense that what one says may not represent what one thinks. Particularly when the topic is lying.

So I'd say the opposite of straight talk would be crooked thinking.