How would you respond? What are the key questions you would ask to collect the group aptitude and criteria? What ep and routes first come to mind?

I'm far from an expert, but I'll take a stab at this one.

What are you looking for our of your BWCA experience? i.e. fishing, wildlife watching, scenery, solitude?
Camping/hiking/paddling experience of the group?
Map reading ability? (some lakes/routes are very difficult to navigate unless you are good at orienteering)
How many nights?
How long do you want to travel each day? (miles and/or hours)
How many people/boats?
Are there any physical limitations? (Injuries, very young or old members in the group)
Single, double, or triple portaging?
Time of year?

As far as routes, it totally depends on the answers to the questions above.
Without the answers, the Numbered lakes would be my first suggestion. Relatively easy portages, lots of site options, decent fishing, and enough people around if something goes wrong.

I'm interested in what questions others would ask.

-RW

Rank these in order of preference....fishing, solitude, waterfalls, pictographs.

Which do you prefer....basecamp style or moving camp at least every other day.

Which do you prefer....long paddling stretches or smaller lakes/rivers with more portages.

That's at least what came to my mind right away to help narrow down the options. Would they enjoy a 1/2 mile portage?

I think the first two questions should be length of the trip and time of the year. Time of the year might not influence where they go so much as it gets them to think about what they want their trip to look like.

Then we need to know how much work are they expecting to put into the traveling. Have they ever backpacked or been in a canoe before? How close do they want to stay to the EP? I wouldn't recommend big water for someone with no experience in a canoe, or long portages to someone who has no experience portaging or backpacking.

Once you have an idea for how long they have in the boundary waters and how much they are comfortable taking on, then you start asking about what they have in mind for their trip. Are they looking to fish, stay in the campsite, or explore? Flatter ground or hills and cliffs?

Once they pick their priorities then you can point them towards a few options that suit them. Personally I always prefer starting with what is possible then going into what they want because getting someone excited about something that might be beyond their capabilities is a good way to disappoint them.