Well, I thinned out the second coat so it'd be somewhere around the consistency of sour cream, and skimmed that REALLY thin. It was just thick enough to fill, but not too thin that it'd run. That filled in everything, and once that was sanded out, I'm done with it.
I was gonna do the sides of the CP top as well to fill in the end grain, but with a router, it's as smooth as I care to make it. If this had been done with any type of saw (jig, circ, sawzall) I'd have had to definitely fill in the sides, but I've decided since this isn't even gonna be the final version, screw it. There's a few pockets where there were voids in the ply's, but they won't make a bit of difference to me in the end.
After sanding, you can see in these pics just how uneven plywood can be, but it's really nothing you need to worry about if you're laminating over it. The amount of filling being done is negligible for your purposes, but for playing on what will essentially be bare wood, it's vitally important. Know what I mean? You'll be putting your hands on the laminate, I'll be putting mine on the wood. No danger to you, big danger to me, kitten-saving-technique for Bones

I'm letting the dust settle before finishing everything. In case you don't know, even with the small amount left over after what you can see is a tremendously thin coat compared to what you'd put on the walls, sanding drywall compound is eleventy brazilian times more messy and dust-producing than dealing with MDF. While I'm not sure of the toxicity of the stuff, if you're doing ANY woodworking without a mask and eye protection, you're an ass hat idiot, and doing drywall is an even higher level of retarditty without those things.
Tomorrow, I'll be running to CompUSA thanks to McCoy, and hitting Home Depot's "oops" paint shelf for something to paint the CP top with. I pass 2 HD's on my way home from CompUSA, so if there's nothing but ass as far as the eye can see at the first HD, I'll just buy the least asstastic paint at the second one. It'll just have to cover the layout marks I'll make for my buttons and whatnot.
I'm not entirely sure what 4-player games (that I'll LIKE) require more than 3 buttons - any help there? I'll be going with 3 buttons for players 3 & 4, and 6 for players 1 & 2. This will absolutely never be used for console-anything, so if even 6 buttons are overkill, open your piehole and tell me I'm wasting money. I'm getting some of the black player start buttons from Peale
(CLICK ME FOR LINK ACTION - CHECK 'EM OUT AND GET 'EM WHILE THEY'RE HOT GUYS!) to throw on there, and naturally, an "O" and a "K" button.......yeeaaaaahhhh

Anyhoo, here's a pic of that big crack all filled in and pretty. Everything's now smooth as a baby's butt, and the second pic is just to show what all is filled in and to give an idea of how it might have felt if I HADN'T skimmed all the irregularities out of the plywood