Most kids love bubbles from an early age, and it keeps going for years. While having them blow bubbles while holding a small container of bubble solution can be a pain (how often will you refill it due to spills???), there are alternatives.
I’m very fond of our bubble machine. Our current one has lasted a few years, and while it doesn’t do as well as some we’ve had, it blows enough bubbles to keep the kids busy a while. My older ones are good at filling it with minimal mess. I like that it makes tons of bubbles to drive the kids wild.
I suggest setting the bubble machine up on an outdoor chair or table, something steady in any case. Warn the younger kids to keep their hands off – trust me, they will make a mess of things if they can handle it, carrying it around the yard, starting arguments when one turns the machine off; it’s a pain. Also make a rule that everyone has to give the bubbles some space to spread out – kids get really mad when someone else is hogging all the bubbles simply by standing too close to the machine.