I'm still leveling the floor, but hope to begin actual hardwood installation this weekend if my wife doesn't murder me in my sleep for taking so long with this project.

When putting down the 15 lb felt prior to installing the hardwoods at a 45 degree angle, does it matter in what direction the roofing paper is placed? Should it also be placed at a 45 degree angle running parallel to the hardwood installation?

two things to note
the paper is slightly tacky and i noticed if i layed out too much at once i would track wood partials or dirt and have to clean up twice.

second when overlapping the paper i noticed when a board spanned the low and high spot it did not seem to go together as easily.

so laying the paper perpendicular to the floor may have been a good idea. What do others think?

Some lay the 15# felt at 90 degrees to the direction of the floor to avoid the bump from the overlap. Some do not overlap and butt the paper joints. There is no hard and fast rule. Do what works best. My problem with running the paper at 90 degrees is: I rack my floors then kick the wood into place while nailing. If a seam in the paper prevents the wood from going together easily, that's a hassle I want to avoid.