So, are you saying to run perpendicular to joists even if it means running perpendicular to the length of a hallway? i'm not sure how that would look, but maybe it doesn't matter.
OK. Here you go: Don not put any wood or laminate in any bathroom or laundry that you want to remain looking nice for a long period of time. Any moisture on top, seeping water leak around the baseboards, and high humidity then low humiditty will eventually damage, ruin, and suck the life span out of the floor.
Regaurdless of previous threads, do not install any solid & nailed down flooring parallel to the floor joists. Always go perpendicular, or possibly at a 45' angle. Nailed down flooring will follow the wavy subfloor and this will look terrible. This may not be the best look for a given room, but will look alot better than a wavy floor.
Some laminates are better than others. Pets are bad on floors. Size and activity level of pets does make a difference.
If you have pets, and you buy real hardwood and want it to remain looking like the day you put it in, you might be in for a surprise. No flooring company or manufacturer will warranty for abuse, negligence, or pets.
You shouldn't need transitions between rooms for nailed down solid flooring. It is only if you have laminate floating floor, and then not mandatory. You could install a "header" piece of solid flooring between rooms to create a different room effect.
I'd reccomend tile for bathrooms and laundry areas.
21yr veteran