I think the carpeted cat walks would be wonderful! I have a friend who lives near Seattle who made these for her three cats and they love them! As to how high up....well...if you're concerned, make them high enough to be out of the dogs reach but not so high that you feel uncomfortable. There have been stories here of kitties spraining legs and such jumping down from high places - or so we suspect, in most cases nobody was a witness so we can only speculate as to why kitty was limping.

Good luck!