Just a note on what is "expected" and the school's reaction. My understanding is that there is a gap (usually around 2K) and parents are expected to donate for the reasons stated above. However, the schools know that some people can afford $100 and others can afford a few thousand extra each year and they expect the ones that can afford more to make up for those who give less. My kids have attended private preschools and now elem. schools and we just give what we think is reasonable for us. It is a huge stretch to send them there in the first place, so I am not embarrassed or worried that we only donate a few hundred extra dollars each year.
Also, I donate a lot of time to the schools and I think that is also a fair trade!
I am surprised to read the OP. 21 new kindergartners at Sidwell last year? This is purely anecdotal, but I heard from my friends who applied to Sidwell K last year that no (or maybe 1 or 2) kids who were not siblings/alumni kids got in at all. At the school my daughter attends there were 12 solid openings for K. There are three classes of 12 kids each. I would be surprised to hear that Sidwell has that many more spaces at that entry point. I also understood (again anecdotally) that Maret has very few spots at K for non-sibs/alumni. I did hear from GDS admissions a year or two ago that Pre-K and K were both amin entry points and they had a bunch of spots but last year I knew about 6 families and none got in there either.
Did anyone's child attend a WIS camp last year? My daughter learns a little Spanish at her elem. scool, so I thought it might be fun for her to attend WIS for a week or two. Do you think it will be worth it for just a week or two or will she need to do a longer session to actually learn any Spanish? Also, do you know where they swim?