I play viola and double bass. DH plays French horn. We go to rehearsals all the time with viola and horn (literally) in tow.

I've figured out how to haul the viola on the 'bent (love the underseat racks) but have yet to figure out how to transport the bass. DH uses a Burley trailer to pull his horn - which is about the size, if not the shape, of a small child.

We chuckle on cold winter nights riding home from rehearsals, drivers are particularly nice and accomidating. After all, we've obviously got a baby in that trailer that needs to get home. I keep waiting for someone to call Child Protective Services on us...