UVSJ = UHF-VHF-Signal-Joiner
http://www.antennasdirect.com/store/...Combiners.html
http://www.solidsignal.com/pview.asp...nna-%28UVSJ%29
http://www.radioshack.com/product/in...ductId=2103923
http://www.amazon.com/Antennas-Direc...&keywords=UVSJ
The best place for an amplifier is at the antenna were the signal has not been attenuated by a long cable run. 100 feet of coax has roughly 6 dB of loss. An amplifier at the far end would be working with a signal 6 dB lower in strength... that much closer to being 'buried' in noise. Because some of the signals to the south are fairly weak, you'll want to do what you can to preserve their quality. Another way to think of this is, Amplifiers can not 'pull' signal from the antenna, they only 'push' the signal through the losses in the cable and splitter connected to the output of the amplifier.
Yes, I am recommending two separate solutions. One for local easy to receive signals south of you. This antenna system does not require a rotator which makes it easier to use as the 'whole house' antenna, no one will argue over which way to aim.
The second system , if you choose to install it, is a high performance deep fringe system that gives you a shot at the much weaker signals from Portland. If you include a rotator in the design, you can fine tune the aim and turn it west and south west if you choose.