Currently I am reading Robert Deakin's Waterlog: A Swimmer's Journey Through Britain and I am loving it.

Also Stephen Hodge & Phil Smith did A Mis-Guide to Anywhere. Check out their other books as well. Will Self did some good writings on Psychogeography.
On the environmentalist note, Robert MacFarlane deserves a praise.

I have some books tagged on GR.
London Orbital is excellent. Check out The Old Weird Albion by Justin Hopper. Calvino's Invisible Cities are not a traditional PG, but it's beautiful book. From the practice perspective Stewart Home has some great books.

www.goodreads.com/review/list/...