Where can I find data tables for lift and drag coefficients of airliners?
My first thought was: Abbott-Doenhoff. They wrote a book with lots of measurement data, and you can find it here. Of course, this was all long ago, but public data for the airfoils of today's airliners are not published.

A lot of data is also freely available in old NACA and NASA reports, however, you need to know what data you want to search for it efficiently.

If you want to focus on glider airfoils, the Stuttgarter Profilekatalog would be my next source, but unfortunately there are still people who want to make money from it even though the work was financed with public money. This is also quite old, and more modern airfoils from Delft University are similarly restricted.

Another great source is the UIUC airfoil database, but here the focus is on section data and not on polars. But it contains many useful links with airfoil data.

And then there is always XFOIL: Feed it with the coordinates, and you get very good simulations of what a wind tunnel would measure, at least as long as most of the flow is still attached. Lots of plotting functions will help to uncover what is going on in much more detail than any wind tunnel data could ever hope to do.