We take a Maclaren double. Which is great, seats recline all the way for tired kids, rain cover will act like a tent in rain showers and its our own pack mule for necessary items/bags.
Of course, we also try to avoid busses like the plaque but its doable.
My dd 4 walked a lot but She sure loved the option to ride when she needed to...last thing you want is a cranky kid that "can't walk another step"