If possible, keep as much of the tile and as many fixtures as possible.
Replacement parts are available for toilets.
The tub and the sink can be resurfaced if they are worn and stained. The biggest problem can be the condition of the faucets, but they can usually be replaced. If not, the entire basin may need to be replaced. Some newly manufactured ones are of high quality and styled to fit an older bathroom. If tile repair is necessary for other reasons, that is the time to seriously consider how much life is left in the in-wall fixtures.