I only had time for a short one...
Warmup: 6 x 75 kick-drill-swim, choice (I did 2 x free and then all the strokes in IM order)
Main set (x 1 only rather than x 2 as assigned; all freestyle and on :20 rest):
150 pace - smooth - fast by 50
2 x 200 cruise
150 build by 50
50 double-arm back cooldown
plus 200 easy back cooldown
1650 yards total
Some useful conversation with the coach on deck about masters swim options. There won't be fall masters swim at Columbia, but it's possible that they'll offer a "lane swim" class in the evening time-slot - this would suit me well. But I still want to find a real masters swim situation, and putting what D. said together with I.'s observations, I am strongly thinking that I need to check out Red Tide. It's relatively conveniently located, relatively affordable and sounds like very much what I want: they have a competition requirement, which I think is great, but welcome inexperienced swimmers also and do a lot of stroke clinics etc. Team New York Aquatics also sounds very good (hmmm, I see one workout is even at the Columbia pool, that would be convenient): bi-gay-lesbian club, but open to all, and affiliated with Red Tide.
D. and I. both also mentioned the New York Flyers running club, so I think I will look into that also when I get a chance. Next few months have book-writing and marathon training as priority, plus school in September, so it may be that this is going to be more what I sort out in later fall and winter...