I've been meaning to rebuild my tablesaw wings and to incorporate a router into one of them. My saw is on a rolling cabinet I built years ago so I can wheel it out of the way and put the sled in the garage. Sure makes it convenient. I currently have a stand-alone large bench top router table I built years ago. The plans for it came from ShopNotes.
You can also find some great router plans for jigs, etc. and a router-table-in-the-wings in Bill Hylton's book Router Magic on page 183.
When I do this, I won't be using a removable rectangular clear plate in the table top. It's too easy for the table to warp over time, plus the plate can warp if made from acrylic or polycarbonate plus your wood can catch at this joint unless it's perfect. I plan on attaching a separate base for my PC router to the underside, then using a set of adapter rings with various dia. openings to accomodate different dia. bits. He describes how to make your own on page 173. You can make yourself a whole set of these + extras and develop your skills.
Finally, Hylton recommends never cutting a slot for a tablesaw miter gauge in the top of a router table: It weakens it and makes it prone to warping over time. I concur.
I'll be using Corian or similar material for new wings as well. Really holds up better than Formica, is easily cleaned of glue drops with a cabinet scraper and looks really nice. I get scraps for free from a local kitchen countertop manufacturer. Granite hasn't completely taken over yet!
+1 on Lee Valley's circular router insert plate + their steel router table and aluminum fence. Really nice set-up!