I'm using a 6 X 4 Crestron HDMI matrix for a design and I have two BluRay inputs that will be about 100 feet away from the headend. What would you use to extend these two inputs back to the switch?

TIA

The same thing I trust for my TV's that are 100' feet away.

This is what I've used with no problems.

[Link: crestron.com]

This is what we have been using and we have had 0 failures.

[Link: monoprice.com]

I have used the Crestron HD-EXT1-C. It is rock solid and can pass RS-232 and IR. It also is powered on one side only. However if using this unit make sure you have shielded cable or their DM-8G wire as this unit is not part of the 8G+ series.
I have also used key digital which are a piece of junk, they first got the pin out wrong so you have to terminate the cables in a weird configuration, and with all of that, I had video drop outs. Another unit I have use a lot on lower budget projects is the SnapAV HD-2CAT-1080P-130 unit with excellent results. This unit requires two UTP or STP wires and it can be powered from one side only.
SnapAV also has a couple of new units coming soon and the one on the link below seems to be pretty good:

[Link: snapav.com]

Regards