Well, I spot lots of other single parents doing the kid-switch thing on Trimet on Friday nights ... and have gotten hit on more often on the MAX than any other place. A woman carrying empty baby gear is the key ;).
(I get hit on mostly by non-dads, which always surprises me since I am carrying around an umbrella stroller that has seen better days ... but I've decided it's because most of the single dads on the MAX are receiving their kids on a Friday night, and are of course focussed on their children and not on the moms who are at lose ends ;). )
I do not consider myself "available," btw, which is the only reason I am 'selling' a location where I might be found ;). Or any of the following thoughts, for that matter!
The other thing I would say, is that my single friends who are open to dating, seem to hang out in the more sophisticated kind of bars, that mix new or at least very well made drinks. Single moms often have gained a certain "take care of myself" skillset that includes "treat myself to things" ... and again, Friday night seems the most frequent moms-don't-have-kids night. Thursday and Saturday in second place. Anecdotally.
Yoga classes and other self improvement activities are another draw.
The grocery store (or any store)--shopping without the kids is way easier than with, and for most women, dawdling over shopping is recreational. And on Friday night, seriously, non-parent single people do NOT prioritize shopping. I almost always hit my grocery store at least briefly on Friday evenings, for take-home treats for myself if not a full-scale shopping trip. (Full scale shopping, I actually usually do on Saturday days.)
For whatever help my highly anecdotal response might be ;).
Thank you for being so responsible to ask the Mamasource folks about the appropriateness of your request, especially since you have already breached the walls of an advice group designed for females ;).