Memphis won't be hard to get at your house: it's only 25 miles to the transmitters, but WMC-DT operates on low-band channel 5, so you will need an all-channel antenna to be sure that all of your stations come in reliably.
I am very much against attic antenna installations, because there is no way to predict good-quality reception in an attic. Attics tend to have HVAC ducting in them, sometimes foil-backed insulation, and if the house has a metal roof, stucco or aluminum siding, then you are absolutely out of luck: bad or no reception. Outside mounting is the only way to insure that you will see good reception on all of your Memphis stations. If you follow my recommendations, I guarantee that you will see everything that you are looking for.
Use a Winegard HD-7082P or a Channel Master Crossfire 3679 antenna aimed due north of your location: use a compass, don't guess! Use high-quality, satellite-grade RG-6u coaxial cable throughout the system. Run the coax to a proper grounding system (shown in the installation instructions attached), then have the wire enter the house. Use a Channel Master CM-3414 4-way splitter-amplifier connected to the incoming antenna cable, then connect the outputs of the amplifier to the cables that will run to your 4 TV sets. The Splitter-amplifier requires AC power, so be sure that you have it available where the amplifier will be located. You will get better-than-cable or satellite quality TV using this formula.
http://www.winegard.comhttp://www.channelmaster.comhttp://manuals.solidsignal.com/AntInstallGuide.pdf