Ohio must be really flat. It's hard for me to imagine you not having anything to look at around your area for inspiration. Come out to Cali for a vacation. Everyone has a sloped lot, but small space, so the retaining walls and landscaping are essential to get any joy or value out of your property.
Start by determining what you want to use the yard for. Are there multiple uses?

workshops
storage sheds
gardens
play space
outdoor kitchen
seating
entertaining
swimming pool

Make a simple plot plan layout and designate space for each function. Give ample transitional space for people to flow freely. Plan to build the retaining walls without moving too much dirt. You can create nice flat terraces by working with the existing grade. It is not really a good idea to bring in or take away very much soil. it could cause erosion or drainage issues with your entire lot.