You do have all the major TV networks available to you from the Portland area. Since some of the stations lie in different directions from you and are far enough away from you to have only moderate signal strength, I believe that your best bet is a fringe-area VHF-high-band plus UHF antenna mounted on your roof along with an antenna rotator.
I have 2 concerns for your situation that we need to address: first of all, WMEA, your local PBS station is only about 6 miles from you, and puts a very strong signal into your location. WMEA is off-axis of the other Portland stations, so a high-gain, highly-directional antenna would be our best bet for you. Because WMEA is so strong, I am a little concerned about using a preamplifier because of the potential for signal overload : we need to use a high-input preamplifier to avoid overloading the preamplifier from the WMEA signal. My other concern is for WPFO, your FOX outlet, which is 60 miles away from you, and it puts a very weak signal into your location. Reception of WPFO would likely call for using a preamplifier to insure a decent signal.
Based on what I can see, I would proceed this way: Use a Winegard HD-7697P VHF high-band plus UHF antenna mounted along with a Channel Master 9521a automatic rotator. Use all satellite-quality RG-6u coaxial cable,and use a Winegard HDP-269 high-input preamplifier, which is highly resistant to overload. The other advantage to this preamp is that it will allow you to use multiple TV sets from the single antenna without incurring signal loss. When you get it all installed, you should see all the Portland-area TV stations plus, if you rotate the antenna, you'll see New Hampshire Public TV on channel 11 and WMUR-TV, ABC out of Manchester on channel 9. I will include links to the equipment, and a good installation guide to help you through the process.
http://www.winegard.com/kbase/upload/HD7697P.pdfhttp://www.winegard.com/kbase/upload/WC ... DP-269.pdfhttp://www.channelmaster.com/product-ov ... 8&catID=34http://manuals.solidsignal.com/AntInstallGuide.pdf