If not for the trees, I would suggest a smaller antenna. But the Douglas Fir, Cedar and Alder common to the area often force us to increase the gain and directivity of the antenna.
The Winegard HD7694P is a good single antenna solution. Start with an aim point of due south. Try this with no amplifier You can add one later if the need is proven.
A premium solution would be an Antennas Direct DB4E and a Antennacraft Y5713 or Y10713. The DB4E would face due south or a bit to the east, to give you the UHF signals available. The YX713 would point at about 190° and would serve up the High-VHF signals (PBS. CW & Fox). Combine the output of the two antennas using a UVSJ.
Start by installing the antenna(s), then before connecting any splitter, check signal quality and tune the aim by connecting only one TV, preferably one with signal metering to aid in aim adjustment. Once the antenna(s) is/are known to produce a reliable signal, add a passive splitter (3-way or 4-way depending on how many sets you'll actually connect). If a signal becomes unreliable you have reason to consider adding a distribution amplifier such as the Channel Master CM-3410. If used, the amplifier is more effective when installed upstream of the splitter, close to the antenna rather than close to a TV.
http://www.amazon.com/Winegard-HD769...ywords=hd7694p
http://www.amazon.com/Antennas-direc...&keywords=db4e
http://www.amazon.com/Antennas-Direc...f+vhf+combiner
http://www.antennacraft.net/Antennas/AntennasVHF.html
http://www.amazon.com/Channel-Master...ywords=CM-3410
