We plan to lay hardwood flooring throughout our kitchen/family room concrete slab. Any suggestions on the application?
Also, this is a very long room. Should the flooring be laid parallel to the length of the room?

You can lay an engineered hardwood on a concrete slab - better if it's a floating floor as opposed to a glue-down as it's almost impossible to get a perfectly level slab. A glue-down engineered floor on a slab with any high or low spots is going to have some floor pops over time. Solid hardwood glued to a slab is going to fail as it absorbs moisture.

Generally, you want to lay the flooring in the shortest direction - this is to make that smaller dimension look larger. This is more important for a long and narrow room. The closer to square you get, the less important direction is. Always remember to factor in fixed items like cabinets as visually, your eye will consider the cabinet as the edge of the room at floor level, not the walls. And finally, since you are doing more than one room you may have to compromise if one room is long in one direction and the other is at a 90 degree run to it.

I did some post Katrina work in Mississippi and one of the projects our volunteer group did was remove a glued down hardwood floor on a slab that had been flooded. Having done this work, I'd strongly recommend the floating kind. Removing that floor was some of the hardest work I've done in a long time.

Glued floors were pretty common in Mississippi and if not for the 3 feet of sea water Katrina deposited most held up well. Before I did any hardwood on a slab I'd want to test for dampness coming through the slab. Tape a piece of aluminum foil or plastic to the floor sealing all 4 sides. If after several days you have water under the foil/plastic you have water vapor coming through the slab and it would probably be best to find a different floor covering. I would do this test in several locations throughout the house including close to exterior walls and near any water use point that may have a under-slab drain or supply line.