I have a DR table (very large, heavy butcher block top style) made of alder wood (about 25 years old) of which I have had the 2 leaves in it for about 18 years. Well, of course, now the center of the table is sagging a little and the edges of the leaves are planed (?) because of having them in there for so long. What I need to find out is what I can use underneath the table to push everything back up to where it should be (I want/need to leave the leaves in otherwise my DR looks tiny) as a support. Any help is appreciated.

What is your style throughout the rest of your home? Check out local antique dealers, eBay, or sites like Chairish to find vintage Eastlake chairs (can be quite pricey, though). Alternatively, consider pairing your beautiful table with modern chairs for an eclectic look. https://www.digsdigs.com/antique-table-and-modern-chairs/

I'm needing ideas for a full tablescape, please! Everything from runner, placemats, all plates, glassware, flatware, napkins, centerpiece, etc. I've attached photos of the table, rug, paint, and room.

honestly less is more, I would consider a new light fixture and wall art. move the bench to the back and the chairs to the foreground. Or if there is a leaf in the table take it out and remove the bench altogether.