I added a shower to a tub last week.
Learned a few things.
1. Tile, not panels. The panels were a nightmare to put in, impossible to align, and look like trash. Tile would've been much easier and looked much better.
2. PEX is awesome. I'll do PEX again for everything. It was super-easy to work with. The hardest part was connecting to existing non-PEX, and even that was easy with push-to-connect fittings. No soldering, no torches; the only threads were on the shower mixer.
3. If you're doing a shower in PEX, the mixer-to-faucet drop must be copper, not PEX. This is because PEX has a slightly smaller inner diameter, and shower mixers are designed for copper, resulting in water going up to the showerhead when fully on. Which is what happens on mine, and googling afterward told me exactly why. I'll spend a Saturday tearing the panel off and fixing it eventually.
I just bought a new house. There's a lot I want to do with it, but it's hard to find time. I may start paying contractors. I prefer doing things myself, but at some point, I have the money and not the time…
Next on my list is turning a room-shaped alcove in the basement into another bedroom. Which is hard, because my city requires floating walls, and it has a drop ceiling.