How to keep networking conversations going?

I've had about a million "coffees", calls, meetings, etc. with associates & VPs and every time there's this awkward silence between questions. 

I try to ask questions based off of what the conversation entails, but when they give me answers I can't follow up on and I've exhausted all the "what would you do in my position?, how did you succeed in your firm?, recent deal experience etc." there's this super awkward silence because I can't think of anything else to ask. 

These always last around 30 minutes. It feels so short and like I wasted their time meeting with me.