Thanks. I was leaning towards avoiding catnip while the kittens are
out, but I was hoping to find some sort of treat for the adults while
the kittens are out and unfortunately catnip is the only thing that
seems to get any attention.

I don't blame you. My cats are like yours; they really don't go after anything
with as much gusto as catnip. But the way mine act, when I let the kittens back
in, they'd be little live punching bags for them.
Yours might react differently. You never know.
Sherry