I finally screwed up my courage last night and did my creekside staircases, both forward and back. I didn't do all 28; I ended up doing only 27 staircases partly because, given the way I walk home, I have to break off the original path, and the new path doesn't have the same number of staircases.*
In terms of vertical displacement, doing 27 staircases is roughly the equivalent of tromping up my building's tall staircase, from B1 to the 26th floor, three times. The creekside walk is a bit easier than the building walk, though, because the outdoor staircases are spaced apart—most about 100-200 meters apart, a couple as far as 600 meters apart. The breathers between staircases make the up-tromping easier, but in the end, by the time I've done my 25th staircase, I'm pretty damn tired.
Fortunately, doubling the number of outdoor staircases wasn't as horrific as I'd thought it would be. It was strenuous: I could definitely feel the effort in my legs. But it wasn't the hellish agony I'd been anticipating.
I may have hit upon an exercise routine that'll suit me, even as we move into fall. Going 14 staircases out and back, instead of 32 staircases out, means my walks now take much less time and distance. This in turn means less strain on my knees and soles (the soles get the worst of it). By switching to 27 or so staircases, I sweat as much as I would on a 36K-step megawalk, but since intensity is more important than number of steps, this suits me just time. Now, at least, I can always get back to my place at a reasonable hour.
If I have to choose between going three times up my building's staircase and doing 27 staircases outdoors, the choice is easy: outdoors all the way, baby. For as long as the weather is clement, I'll work out à la belle étoile, as the French say.
*What I mean is that, when I'm initially walking west, I do all the staircases on the north side of the creek; when I turn around after Staircase #14, I stay on the north side until I get back to Staircase #3, after which I have to cross over to the creek's south side if I want to walk my preferred way home (behind some apartments, where there's a minimum of people). Crossing over costs me a staircase; to add a 28th staircase to my path, I'd have to double back somewhere, and at that point, late in the walk, I'm too tired to think of doubling back.