We do have bars, but they tend to make me need to "go," if you know what I mean. I ended up just eating regular food for the day, though I went very easy on everything.
We were on the bus for almost six hours total (three hours there and three hours back) so I was pretty careful about what I ate and drank, because I didn't want to have to be the one hogging up the bathroom in the bus.
Fortunately it was a chartered bus, and therefore had a bathroom.
Now I'm thirsty and I'm chugging water, which means I'll be up all night in the bathroom.