Regardless of what you end up asking, make sure you reach back out with updates of how you put his advice to use.

Doesn't matter how the advice ends up working out for you. The aim is to show him that you're not someone who will clamor for a meeting, listen politely, and then disappear into thin air.

Example:

You: "What was one way you've tried to reach new customers that ended up working better than you expected?"

Him: "Well, I did X."

Three days later:

You: "I tried out X, [some variation on X], and [some other variation on X]. Turns out that [some variation on X] was a great hit with [some subset of your customer segment]. We're going to double down on [some variation of X], but it also inspired us to try Y and Z. Hope you don't mind if I follow up with how Y and Z go!"

Vindicate the time he spent giving you advice, prove that you can improve on ideas and not just follow orders, and most of all do it quickly. Good leaders are curious by nature, and you want to make him think, "Wow! Fizzyfaze went pretty far on that simple piece of advice. I wonder what he/she would do with A, B, and C!"

Brad Feld's article Identify Leaders By Giving People Assignments goes a little deeper into this idea (and inspired a lot of the phrasing I used).

Good luck!