Hi,
We've also had the same discussions about crates and pens. Our little fella Harvey arrives in 3wks!!!!!
Think we've decided to get both and build the pen around the crate.
Pros
1. Gives the puppy it's own space.
2. Gives you somewhere to put the puppy while doing house work, etc. without locking him/her up in a crate.
3. If you decide to leave the crate door open at night, the pup will (hopefully) do it's business in the pen on newspaper, and not in the crate.
4. The list goes on...
Cons
1. Initial cost is a bit more.
2. Takes up more space.
Hope this is some help.
Simon