I ask a few simple things like how long they've been together, how they got engaged, and what their wedding will be like, but that's about it. I always try to allow my clients to pick locations/vibe. If they're stuck on locations I can suggest things, but usually I try to get them to think of things they either want their photos to 'feel' like, or pick locations with some sort of significance.

For instance. Here are my latest engagement sessions.

http://benjhaisch.com/blog/katie-dom/
-They took me to a trail right by where they got engaged and then a neighborhood right near where they live

http://benjhaisch.com/blog/carolyn-miguel/
-They wanted some variety and more of an 'editorial' feel, so we shot some regular images up in the mountains and then headed to the desert where we snuck into a rock quarry to shoot some images at sunset.

http://benjhaisch.com/blog/chelsea-mathias/
-These guys are from Vancouver, Canada, but trusted me to find some good outdoor/natureish locations near my home and then had the idea for the holi powder which was pretty awesome.

Hope that helps.