Well, since you asked, the following is my opinion and may not be shared by others and hope you'll take it as constructive. While it might be deceptive from the photos, I think the whole base is too massive. It appears you're using 1" or thicker lumber where I would use something less than 3/4". The different thicknesses of the side/end pieces may be evident even if you lower the top. In the future, if you used dados rather than mortises for the support pieces, I would stop them before the top so they are not evident. You may be planning some more work on these but as they are the support pieces are too thick. What I would do is sculpt them - clean up the edges with a spindle sander ( you can get an inexpensive attachment for a drill press if you don't have one) maybe slice off some width above the dados and use a round over bit to make them look more like a wine glass.
The more I look at it, the less objectionable the size of the base as it will be less over powering if finished like the beautiful slab.
Thanks for the work in progress photos.