So on the first floor there is a full bathroom without an access panel. I would like set up the panel, but would hate the look of the access panel on the first floor which is built into the living room. Can I set up the access panel underneath the bathroom in the basement(ceiling)? Does that violate any code and if so any ideas on how to minimize the appearance of access panel on a first floor wall?
You can add the access you want in the basement without worries unless your basement is a garage (like a daylight basement). If it is a garage then it would need to meet fire code, but if just an environmental space you could create your access similar to a standard scuttle hole for attic access, but hold it in with a few screws. As far as creating access in the wall of the living room, I have seen some very artistic covers for electrical panels in walls (that do not need tools to open) but could do the same for plumbing access. Think of a picture frame on a hinge that could be opened as a possibility.