I use poplar for painted face frames. It takes paint very nicely and is harder than softwoods such as pine, so not damaged as easily.
Regarding pocket screws, if not using them what sort of joinery did you have in mind?
For the boxes, traditional methods would be nails or rabbets and dados fastened with nails. I prefer Festool dominos, but the tool may be too pricey for an amateur or a one-off project. The main issue I have with pocket screws in this application is that you have to be careful to clamp the parts so that they can’t move while you drive the screws else the screws may pull things slightly away from alignment. With a proper jig, boring the holes is reasonably quick.
For face frames, the traditional joinery would be mortise and tenon or perhaps dowels. Again, the Festool domino is essentially a loose tenon and serves well in this location. Pocket screws also work, again if you are careful to prevent the parts from moving while you drive the screws.
For fastening the face frames to the cabinets, the most common choice is nails, often with glue as well.
Well, considering what Dave had suggested, and from what I’ve learned from YouTube, I thought I’d use nails/glue, and then screws for anything that might need to be removed (for access) later, for emergency purposes. Actually the only panel I imagine I might need to remove would be the vertical face board at far left of the unit, since I plan to run the LED lighting harness up that side.
I was kind of dreading the dado cuts for the shelves because (a) I don’t own a table saw, and (b) I don’t know much about routers. But I did find this YouTube about cutting dados with a router and a home made jig: https://www.youtube.com/watch?v=ycp9fDPO4SU
I’m beginning to understand why Ikea furniture is so popular. You can put it together in about an hour!
I was referring to joining the case parts. Glue would be plenty but small nails can take the place of clamps to speed up the assembly. Pocket screws are good for joining face frame parts if you don’t want to use proper joinery.
The way you’re putting this together, I don’t think the plywood thickness difference will matter. It can come into play when multiples add up, usually left-to-right, but here that’s not an issue.
Looks like you’re building this in 3 sections, L-C-R. Makes it practical to move around and get it into the room. But your “countertop” shows a break right at the centerline. A model mistake I presume.
In the uppers, you’ve doubled the plywood verticals. Is this really necessary? The faceframe stile on these can still be like 1-1/2-2" wide, if you only used a single panel here. Or maybe I’m missing your rationale for this.
Nails and glue can be plenty strong enough, but think about how you’ll hold the parts in exact position when you nail them. I’d think about making “spacers”, that represent the inside width of each opening, to hold those sides in position while gluing/nailing. Could help keep your cabinet widths in control while there’s slippery glue! Same for holding the shelves in position if they’re fixed, not adjustable.
And building this on separate “base units” can be a big aid to getting the assembly plumb and level. Suggest making your base box as one whole wide one, with a way of leveling it before the carcases go on it. I uses adjustable leveler feet, but you can get by with wedges and a little bit more work. You level the base box, add on the big carcases, then your baseboard goes on last just like the crown.
For mounting the TV, a slide-out is a lot of work. I agree a swivel mount is most convenient, but a pair of French cleats will do it too. Yes TV’s are light in weight today. If you put a back on that cabinet, but leave the back an inch or two from the wall, you could feed cables up behind that back so they’re hidden. Just leave a big hole (like 8-10"!) in the back to get the cables thru, locating the hole behind the TV where it won’t be visible.
A handy thing to look up is the Sagulator. Yes it’s a real thing. Will help you figure if/how much your shelves will sag, based on the material, their size, and the load you’ll put on them. Just google it.
I used a double-wall on the verticals because I wanted to use 2-1/4" wide face frames on the verticals to give the unit a visual feel of weight and strength, and at the same time, I wanted the side edges of the face verticals flush with the box walls, so there would be no annoying overhang to catch on the book residing on the ends of the row, when I go to slide them out.
I certainly understand wanting the appearance of weight there, and if you want them to not get in the way that’s fair enough. U usually do it the other way, it makes the shelf clips less visible if you’ve got adjustable shelves, but no argument with doing it the way you’ve chosen. Good luck with it!