I was all ready to say "get the 66" tub", but if it's only for the toddlers and you never use it, a case could be made for the large sink/small tub setup. If it were for you, I'd choose a small but elegant 24" sink and go with the larger tub. Maybe it's a good idea even if it's just for the kids. Something like a vessel sink vanity (pic below) takes up only 24" of width, but has plenty of storage space, and you and everyone else who sees it will think "wow, nice sink!" instead of "gee, the sink is too small". If you're on a smaller budget, Ikea's Hollviken or sinks look and work great, and cost under $100. Another good option is a which makes the sink feel much wider than it is by extending over the toilet. Get one of these, and every time you stretch out luxuriously in your 66" tub, you'll be glad you didn't get a 30" sink....

Since you have 3 bathrooms that sound quite large, I would leave a tub in one of them and then do exactly what you want in the other 2 bathrooms. Whoever designed your house sure did love the long vanities! I'm stunned by those measurements. It could look a little odd to have counters that long with just one sink, so I would consider adding tall storage cabinets (if you could use more storage) alongside a shorter length countertop/vanity. As for one or two sinks, I'm building our new main bath with just one, because I like to have counter space to spread out on. That's fine for the way we live - my husband and I never need to be in the bathroom getting ready at the same time. Nor did my kids ever have a problem sharing a single sink in our previous house. But some people would refuse to buy a house that had just one sink in the master bath. I don't think there's any one right answer for this.

This long and narrow bathroom reminds me of the one I grew up with in Brooklyn. It had the same problems you are facing. I highly doubt there is a radiator in this bathroom. The OP can comment if it exists or not. The large diameter steam pipe in the corner is a typical set up for bathrooms in old buildings. There is probably one thermostat controlling the heat for the entire building. The apartment above does not get to set its own temperature. How warm you apartment is in the winter is determined by what floor you live on. I agree if this is the only bathroom then it should to have a tub. I am not sure if re-configuring the tub is going to lower the resale value on a $1M+ coop in NYC. Putting up the wall between the tub and the sink makes the shower more functional. But it will make the bathroom look smaller and block some of the light from the window. I still think if you are going to move the tub the something like this one at Home Depot could work. It is 6 inches shorter than a normal tub. You will need 54 inches from stud to stud which may be possible once the plaster and lathe are removed from the walls. You could install the tub 8-10 inches away from the window wall. A shelf could be built between the tub and the wall and covered with tile. That becomes a place to hold your shampoo bottles and soap dish. Most of the steam pipe would still be exposed and will keep the bathroom warm even with the shower curtain closed. The shower head and controls stay on the same wall. This will open the space to put in a 36 - 48 in vanity with a granite counter top and a wider medicine cabinets and better lighting. That will give you ample storage space. Something that was not an issue when this bathroom was laid out 100 years ago. Have you asked any of your neighbors if they have remodeled their bathrooms? It would be helpful to get ideas and see how they dealt with these challenges.

Any suggestions or some kind of storage for towels, bath things, etc? Good. You've started down the path of discovering why these pricey bits of sculpture maybe aren't the best idea to ever come down the pike. Where to put the soap. How to clean 'back there'. Hired help? Increase liability on your homeowner's policy. No hired help? Get a lower deductible on your health insurance. How to replace/ repair the faucet. Belly board across the top of the tub? Specific to posted photo--that attached towel bar increases how far you have to step to get into the tub. is almost guaranteed to inflict wounds on nekkid bodies and makes it even more difficult to scrub out the tub when you're on your hands and knees and having to lean over it. You live somewhere in the vicinity of the frozen tundra and discover that taking a bath in the winter is a mite chilly despite the fact that you spent $5K on quadruple glazed argon filled state of the art windows. Uh, oh, now I need a bigger water heater. You're environmentally conscious and have the latest and greatest front load washing machine that does an amazing job of cleaning your clothes with only 2.5 gallons of water and a water-mising dishwasher but, for some reason?, your water & gas bill keeps increasing. Fast forward a few years when the tub starts screaming late 2000-teens at you (remember The Garden Tub), when you realize that the tub has a thick layer of dust and lint because you use the shower every day and you are willing to admit that the tub was maybe not the best decision you ever made...Now, how do I get it out of here, how may people is it going to require & what to do with it when it's outside? Argument in favor of The Garden Tub is that those are/ were (may they RIP) mostly acrylic/ plastic beasts that you can/ could Sawsall to pieces in the house and easily tote them outside where you could continue to cut the big pieces into pieces small enough to sneak into garbage bags for curbside pickup, sparing you tipping charges....