Which way is the slope. If it slopes toward the house, that is a major issue that should be thorougly addressed by architect and builder.
If it slopes away, the first suggestion is a walkout, obviously. The second suggestion is to try to locate it on the lot, if possible, to get the best flat area in back. The final suggestion is to make sure the builder keeps all the excavated material on site for your backyard. He’ll have to put up a couple or 3 silt fences, and the best suggestion is for you to hydro some wildflowers over it, given it is a decent loam.
On sloping yards, use an excelsior blanket when seeding, or sod the entire yard beyond where you will be mowing. Mow only the flat areas.
My Mom and Dad have a similar walkout/hill yard, and they don’t have much of a backyard, but they get to watch a lot of wildlife.
