I am getting ready to install 3/4" hardwood over 3/4" plywood. Some installers are saying laying the strip perpendicular to the joists is better structurally but not mandatory. Others are saying the strip "must" be layed perpendicular to the joists. Aesthetically I would prefer parallel. Anybody have an opinion on this?

If you wish to install the flooring parallel to the direction of the floor joists, you can lay another layer of 1/2" CDX plywood over the existing subfloor to stiffen it up OR if you have access to underneath the subfloor, you can add 2x4 blocking between the joists flush with the underside of the subflooring to support the subfloors. Alternately, you also can lay the flooring at 45 degress to the joists and not have to add plywood or blocking. If you lay the flooring parallel without the above suggestions, it is a risk.

Thanks Gary,
We have decided to take the easy way out and talked ourselves into going perpendicular. Thanks again for your advice.
Johnnie