Googled it and found that less than 10% slope is ideal, so in our case, we're good!

Be sure to take the slope into account when you build the house. Putting it in the bowl is begging for basement leakage. Are views or wind an issue in that spot?

We'll be at the mid-high level of the surrounding area,, and the highest point of our lot. The surrounding 32 acres have developed a road to allow water to flow into drains along the road and down to our bowl. The bowl hasn't been wet in the years that we've been watching the lot. The driveway will slope up very slightly to the house, though will make it as gentle as possible as steep drives have been part of our problems in the past, and not helpful in MI winters! Also, I think we're seeing the water flow in the contours, and will be avoiding those indented areas of our contour plot (though theyre really only at the east of the lot).
The bowl is about 3 acres from where the house will go, and is partially an easment, so house in a bowl.
We got a 'problem lot' at a great price. The lot slopes, has the large easment, and is a corner lot. The lot is over 4 acres though, wooded, and the bowl/easment is the area closet to the road (where DH is planning a driving range!). The bowl area leaves us a buffer from the road, and the easment doesn't bother us at all. Sunday we went to see the lot, now that the leaves have fallen we wanted to see the view to the road. There are still plenty of trees for privacy. The lot was almost half the price the lot directly next to us to the west. Yet we're still about a mile from the groccery store and village. And our lot appraised above our value, so we're happy. (I'm super excited, can you tell?!)