Justin - I bet your more confused now than when you started. Lets confuse you a bit more.

I suggest the big cities are actually relative deserts in terms of folk music of all kinds. The hearts of folk music in the UK is in smaller cities and for the most part towns and villages. For example if I limit my self to a 3 mile radius, I can go to a folk club 4 nights a week, and on 2 of those I have a choice. That just wouldn't be true in a city.

This will make transport a particular difficulty because music tends to get going around 9pm, peak around 11pm and often finish near 1am. If you want to talk to people you definitely want to be around until the death. Public transport at that time doesn't exist in most locations where there is a folk club.

If I get it right your looking for participation events - sessions and singarounds. Instead of picking a geography and trying to make your project fit the transportation patterns, how about asking if people will volunteer to host you - put you up for a night or two and take you to 2 or 3 local venues. We are a friendly bunch (I hope) and many are used to providing B&B for singers and the like. If you book in advance travelling between locations by rail/bus isn't that expensive so you could pick a few who volunteer and then travel between them.

If your project includes dance you should consider including Morris Sides, they are very social beasts.

Simon