Wow, thanks for the attention and advice.
I don't have firm plans yet. This grew from tracking down a leak on the other side of the wall, which has plumbing for laundry, outside faucet as well as a bath above. I expect the downstairs was left unfinished by the original builders and done DIY at a later date. They had a fiberglass shower surround basically unattached to the house drain with some odd framing to support it as it was somewhat smaller than the space available. Before firming up the new shower plans I wanted to make sure of what is available and what I'll need to deal with so I don't overreach or plan something undoable. At some point we did intend to redo this bath, just not this soon. So I'd like to have something that will work with future renovation of the rest of the bath too. The toilet is kind of awkwardly situated. It looks worse in the sketch than reality but does seem to preclude a door rather than curtain without making some bigger changes.
The drain is off center by a couple inches which I figured would cause grief with a prebuilt pan, and it seems a tiled shower as big as possible in the space would be nicer which is what led to me to figure on making a mud/tile pan.
The more I look at idea books and remodel websites like Houzz and many others, the easier it is to start thinking a bit grandiose. I'd like nice, but also not too spendy and not too complicated as I am intending to do as much as I can myself. I put in a jetted tub and shower last year where previous owners had taken a regular tub/shower out to make a laundry area (which I put back downstairs). That went well. The tiling wasn't too fancy, some design accents and a premade shelf and that was kind of fun. I've done various PVC as well as copper sweating then and for home plumbing repair over the years, and feel pretty comfortable with that. I'm sure no pro in any of this – not up on the latest (or even most of the old ways) but try and take the time to learn and avoid mistakes.
So my general idea for this shower is still pretty flexible and definitely open to suggestion and advice. I was planning a basic mud pan – like is shown on various how-to sites and books: preslope, rubber liner, final mortar with a 3 piece drain and tile. I can certainly see the advantage to using a material like Kerdi or Nobel and am considering that once I look a bit more at price and availability/shipping. Along with the mud pan I figured on using concrete board/wonder board with plastic behind for the walls. The space above the ledge from the foundation blocks just seemed a natural spot to have space for a decent sized nook. I'm aware as an outside wall it'll be colder, but the same wall in the bathroom doesn't have issues with that and it'll allow for a slightly deeper nook. I expected to build that along the lines of several how-to's, size somewhat depending on what we choose for the tile. I was wondering if fiberglassing the 2x4 and plywood box might make for better waterproofing, but I'm not sure how tile would do with that. On the same wall I was thinking of a narrowish (10â€) bench, built in with the pan ending at it's base. I understand too what jadnashua is saying and haven't ruled out using a premade bench and/or nook insert too.
I was thinking of marble or granite tile for the bench seat and nook bottom as well as perhaps the top of the entry curb. It'd be contrast/accent to the rest of the tiling and would have fewer seams than the 6†tile I was considering for the rest.
I hadn't even thought of other than the basic drains, but I do like the looks of some of these others, especially that tiled one. That seems very doable. I like the looks of that Noble flashing/divot drain. I have to look at that a bit more.
Again, wow! thanks for all the help.