I'd rather have too much than too little. I'm currently helping DD2 redo her MBath. It originally had a 72" double vanity with a pony wall between vanity and toilet. She wanted the pony wall gone, and we decided to go with a 60" double vanity. She'll still have enough counter space and the room won't feel so cramped. Since we're working off the existing sink plumbing, we decided to work from the one closest to toilet, instead of the other which is closer to wall. Vanity won't look shoved in the corner. This eats up a little of the space she would have had, if she had worked off the other faucet plumbing, but the space wouldn't have allowed for a floor standing cabinet for storage, so... Just make sure the 30" gives guests enough counter space.

I used to have that placement before reno of our small bathroom (5x7) and did not like it. The vanity itself was much smaller because of space needed between tub/vanity and vanity/toilet vs one side of vanity being on the wall. The toilet couldn't be right on the wall as well, so there was a lot of wasted space. Also, our door opened up on the toilet not the vanity. I switched to more traditional order of tub, toilet, vanity. There is much more usable space now. This required modifying the pipes for the toilet which is not cheap, so make sure you factor that into your decision.

alexashome- It sounds like your plumber is incompetent and/or lazy. Modern toilets typically measure a bit less than 12" from the back of the toilet to the center of the outlet, which is called the offset. If the distance from the wall to the center of the sewer line in your floor was substantially greater than 12" (which is possible in an older home) he should have explained that you would have this problem and offered suggestions. The best option would have been to move the hole in the floor closer to the wall by getting at the sewer line under the floor and re-doing it. If that is not possible, then an offset flange would get the toilet 2" closer to the wall. There are also some toilets that can be ordered with a 14" offset, rather that the standard 12", and the combination of that toilet with an offset flange would allow you to have the toilet up against the wall without redoing the sewer line. As for the toilet not being level, this can be caused by an unlevel floor or a toilet flange that is sitting too high. If your situation is because of the flange, the plumber was negligent in not setting the flange lower (which would been more work and more cost to you). If your situation is because of an unlevel floor, the plumber was negligent in not using plastic shims to level it and prevent rocking. If you decide to follow any of these suggestions, use a new plumber and not the hack who did the work you are unhappy about.

Chiming in from Canada here. Having the toilet so far from the shower is very weird to me. I would not like them separated, but like you said, it’s done differently traditionally in New Zealand. That said, your current layout is not like this so whoever built your home (whenever that was) didn’t think it was important enough to separate them, so why do you feel the need now? When you bought the house, did it almost make you not want to buy it? Also, 10 years from now things may be very different. Perhaps a new immigrant will buy your house and will prefer to have the toilet in the bathroom as that is what they are used to. For me I would keep the layout as it is and save the money. As far as the bathtub goes, yes they will continue to be important for young families. Maybe a shower/tub combo is an option? Or could you enlarge the bathroom by making the laundry room smaller, and add the walk-in shower while keeping the tub, sink and toilet where they are? Again, I know nothing of the New Zealand housing market so you probably need to ask your realtor. But from my perspective it’s better the way it currently is.