Thanks for the compliments! This is a fun collection to work on and is doable for any condition, depending on budget. With 66's available for < $200, even around $150, it's worth holding out for the nice ones. Granted, there are some poorly struck 66's out there (even P mints), and those are best avoided.
To answer another question, no nice 23-S yet, but I've picked up a nice XF-40 '28-S and and AU-55 '29-D. I'll post what I have on my 1916 through '33 set eventually. I'm sticking to nice circulated grades there.