Welcome guinny. If you aren't sure about I-75 there aren't many alternatives if you're through Ohio. About the only other option you have might be to cut over to Louisville via I-71 or I-64 to I-65 and go down through Nashville and cut back on I-24 to Atlanta & hook back up to I-75. Or you can go south through Montgomery, Alabama to US231 down to I-10.
From my side of Michigan we use I-65 through Louisville, Nashville, and Montgomery. It's is much flatter than I-75, although the main elevation issues you will face on I-75 will be in southern KY and northern TN. Take it at your own pace. If it's slippery, pull over somewhere until the sun warms the road surface.
Safe travels!