We do both. Like you, when we had one child, it was certainly
easier to drop everything and run off- and we did so all the time;
not so much with three!
However, my kids are all older teens now and I've found
that as the kids get older we're able to be fairly
spontaneous again- providing they don't have anything planned
for the night/weekend, etc.
It also helps that I taught them to be responsible for packing
their own gear when they were small and that we store all of our
camping gear in one or two large plastic tubs. If we want to take
off for a bit we just need to throw the tubs in our vehicle and
away we go.