I currently have 10 pipes in the collection and have a rotation of sorts, although not strict. I typically won't smoke a pipe more than one day in a row, but typically smoke two bowls. My Ferndown has pretty much become my Sunday pipe, as it hangs just right for reading the morning paper (and is too big to travel).
A new pipe gets broken in over 4-5 days, than rested.
I'm pretty good at regular cleaning after use. They always get a cleaner through them and a paper towel wipe to keep the cake minimal.
As a frequent traveler, pipes that fit in my single bag get the most use and I tend to look at pipes in that size. I travel with three things - my pillow, pipe and a book. It's pretty comforting to have an old friend along for an overnight. My largeish suitcase always draws comments from colleagues until they see my pillow takes up 90% of the room. I do have a multiple pipe bag, but just use that for vacations.