Hello and welcome!
You are close to the stations you want and their signals are very strong, so you should be able to get the Cincinnati and Dayton pretty well.
I'd recommend something like the Antennacraft HBU-33 in your attic pointed at Cincinnati. The HBU-33 is ideally suited to channels 7-69 which are coming from Cincinnati. It also has a little bit of gain through the "back" side that ought to be enough to allow you to get most of the Dayton station too.
Since your signals are so strong, there's a good chance you'll be able to drive 2-3 TVs without the need for amplification. Just use a regular F-type splitter to drive the signals. Keep cable lengths short to minimize signal loss. If you end up with extra unused ports on the splitter, cap them off with a 75-ohm terminator (like
this).
You can try everything without an amplifier first, and add one later if you need to.
If you decide to add an amplifier, be sure to pay attention to each amp's Noise Figure rating. This is how much noise the amp adds to the signal in the process of boosting it. "Good" amps will usually have a Noise Figure of 3.0 dB or less. Lower is better.