I did a hot air balloon ride earlier this year over the Serengeti in Tanzania, Africa. I brought two camera bodies and two lenses with me on the balloon. On one body was a 24-70mm and the other was 100-400mm. I used both equally. I recommend not changing lenses once you're in the air. I also don't recommend a polarizer. I had absolutely no time to even think about putting on a filter. And besides...I would have been too afraid to drop it.
I'm not exactly sure what you plan on shooting, but for me, wildlife was there, so the longer focal lengths helped quite a bit. Furthermore, with the long lens, I was able to isolate images off in the distance at the horizon.
The other consideration is shutter speed. Because you're moving pretting good, I recommend 1/500sec or faster. Shooting shutter speed priority helps to maintain this. But you'll have to watch your exposure closely because if you're shooting into the sun versus away, you'll have a huge difference to compensate for. To get it to work, you may have to adjust your ISO or quickly flip to aperture priority. Anyway, as for your ISO, I started off at 800 and gradually lowered it as the light brightened.
Just keep in mind that it's a juggling act for exposure. You have to be quick on your toes.
Anyhoo...here are my keeper images from my hot air balloon ride:Dust and TreesBalloon FireHot Air BalloonMigrationMoon and ShadowTwo Pair