How big of an event did you have in mind?
However big it gets, we should have an answer for it. I was hoping for 20 riders, but I doubt we'll get that. We have at least six riders who have expressed interest and several definites, I don't see a problem with any sized group smaller than 50 really. Maybe I'm deluding myself but riding at or near the speed limit on relatively quiet roads, I don't think we'll run into problems.
I'm afraid if we were to make too big of a production out of this, some new riders might get intimidated and shy away. 
I would hope not, but that could be an issue. This will certainly be a well spaced ride as in two seconds apart.
We will need to consider routes. Some new riders probably would prefer roads without twisties. Some new riders, like those with M1's have some restrictions as to what roads they can ride on.
Right. I figure we should make the ride about 1.5 - two hours to make it worth everyone's time. Bearing in mind a 15 minute stop halfway through to ask how everyone's doing, maybe. So, routes I was thinking of but bearing in mind that I'm not the only voice here:
- Taylor Kidd to Wilton Rd., North past Odessa, East through Yarker, take more indirect route to #15, North to Verona, stop for break @ gas station. North to Westport Rd., over to either Bedford or #10, back to Kingston on Unity Rd. to #15 and South back to meeting place. Longer ride, with lots of twisties but other than the cliffside @ Westport Road, nothing challenging ridden at a newbie pace. Personally I think this would be a really exciting ride for a new rider.
Alternatives
- We go West to the Ferry on Loyalist, ride into Picton and back through either Northport or along the #49 and down Green Point road, back #2 until Napanee, then Palace Road -> Camden East -> Yarker -> Harrowsmith -> Sydenham -> Kingston.
- We go North on #15 to Unity, #10 to Westport, Stop , East to Crosby, South to Sunbury Rd., South to Unity, Sydenham Road, Kingston.
I'm trying to keep from throwing something in there like Desert Lake Road or Jones Falls Road... or even the Landsdowne Sweepers, but make the ride picturesque and interesting. That's the whole point, making it TOO easy will make it boring and won't show people some of the better roads to enjoy. Bear in mind that sticking strictly to speed limits, this trip will take much longer than you're used to.

Also, there might be two types of "Newbies". Those who are experienced riders and new to Kingston. Therefore want to be shown some good roads in the area. Then there are first timers who are new to riding all together. Perhaps there should be more than one group go out.
I had hoped and planned to take more than one group out right from the start, and this had been mentioned before as well. I think any of the people in the rider's group could lead a slightly more spirited and/or slightly more challenging ride. For the early-days riders, we'll need a leader AND a follower, or at least a follower who can generally block traffic if there is more than one beginning group. I wonder if anyone has any orange vests...
Logistically, it's pretty obvious that a leader's rider meeting is going to have to take place the morning of the event. And a little preaching needs to be done by the leader of any group.