Not sure if anyone still cares, but quick update: I went ahead and
bought Benjamin Moore's top-line eggshell paint. I primed the orange
walls using BM's stain-blocking primer, but painted straight over the
white walls in the bedroom.

In both rooms, the first coat of paint covered so well that I didn't
end up painting a second coat. Of course, like I mentioned, (1) I don't
get much natural light in either room, and (2) I wasn't too picky about
my own workmanship, so it might actually be a shoddier paint job than I
think. Still, I'm mostly happy with the results (the blue didn't turn
out to be the exact same shade I had in my mind, but it's acceptable).

In any case, I'm definitely a fan of Benjamin Moore now; although this
is the only paint I've used so far, it seems very good paint for sloppy
novices like me to work with - easy to put on, quick-drying, great
coverage, tolerable smell, and fairly easy to wash off of skin and
hardwood floors.