In your situation, I'd hire a General Contractor. The most important sub-contractor to that GC is the tile professional IMO. Don't let the GC hire an inexperienced tile "guy." You should have a certified, experienced tile professional on the job. That person generally handles all the prep, waterproofing, and tiling. The GC will decide the allocation of tasks between the different sub-contractors. Here are two place you can look to find a certified tile pro in your area. Often times, really good tile pros are not certified by these organizations, but they are still experienced a good tile pros. In that case, you'll need to see their previous work, and ask them to explain to you how they do waterproofing. Make sure that your contractor spells out that "all work is to be done in accordance with manufacturer's instructions, local building codes, applicable TCNA, ASNI, and industry standards."

https://www.tile-assn.com/

https://www.ceramictilefoundation.org/certified-tile-installer-cti-program

https://www.tcnatile.com/products-and-services/publications/218-english-publications/188-handbook.html

The question you should ask is whether you have the experience to know how something needs to be done and how to evaluate the work?

Do you have the experience to order everything that is necessary and to coordinate that everything is on-site and is correct and as it should be.

Do you have the ability and time to coordinate the workmen and supervise them - and as stated - make sure they are doing their job correctly.

If not, your best move is to hire a GC. If you hire a great GC, the odds are that the workmanship will be first rate and everything will be done correctly. He will take responsibility for ensuring that everything is ordered and is correct and that the workers are there when they need to be.

In my jurisdiction, bathrooms need to be inspected multiple times. It is the GC (with the appropriate tradesperson) who will meet with the inspector. A good GC will know exactly what is necessary to get something approved because they have gone through the approval process multiple times.

I agree that the tile installation is probably the most critical, although replacing an old cast iron tub is also not an easy task. You may not need a permit if all plumbing fixtures are staying in the same place and the wall framing is not changing; however, every city has different rules.

There are old and new methods for prepping and waterproofing walls and floors for tile, and the new methods work a lot better. My preference for a new installation is to use the Schluter products to waterproof and prep both walls and floor, but there are other companies with equivalent products.

Its also important to get a good carpenter in there to look at framing before the tile prep, because he/she can ensure walls and floor are as plumb and level as possible. Tile installation goes much more smoothly if the installer is not continually having to adjust for bad plumb and level walls and floors. Sistering a few studs or joists to level things up is very easy when its already open.

Bruce

Thank you for the feedback. Bruce your mention of making sure walls and floor are plumb was my concern. I was unsure if that would be the job of a tiler or carpenter. We had connected with a tiler and a plumber (independent of each other) about a year ago that were highly recommended on our town FB Pinboard (then we had to delay the project). I found it reassuring to actually talk with the person doing the work rather than the contractor.

I found that with another renovation with a GC that we still had to be familiar with how things needed to be done in order to evaluate the work. We were monitoring the work and checking in with the workers directly. I can't say that the GC reviewed the end result each day for accuracy. Several times we brought something to the GCs attention that if not identified by us after reviewing that day's work, would have meant a bigger disaster. However I can see that we would become the mediator with independent subs if one subs work impacted the others.

What I may do is ask the tiler or the plumber (we liked both) if they work works with a GC when there are multiple subs involved.

Thanks for the food for thought!