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....

I've had my eye on a Toto Clayton tile-in airbath for a while. I can't say they are any better than a kohler or other brand; we just stumbled on it because we'd already bought a toto clayton toilet and thought we might stay in the same line as we redo the bath. As for the step depth, I remember reading about the design work of Shusaku Arakawa and Madeline Gins, who believe that we can defy death through architecture. They believe that houses that are physically challenging to live in are better, and their designs are frankly crazy by any standards we are accustomed to. I rolled my eyes when I first read about their work. One of their designs required crash helmets and hiking boots to tour, and some visitors broke bones. (I couldn't make this up if I tried!). But as bizarre as their designs are (you can check out their website at reversibledestiny.org), it did make me start to wonder, what if our houses required us to move and stretch a little more than they do now? So while I don't want to live in a house where visitors regularly fall and break bones, it seems to me that a navigating a deep step into tub is not asking for that much, especially if you have grab bars in the right places and a non-slip floor next to the tub. I suppose an indigenous hunter-gatherer would roll their eyes at our sedentary coddled lifestyle and think we're crazy to live in a way that allows diabetes and heart disease to become epidemic. So go ahead and get that airbath. Maybe you'll live a little bit longer :-) Here is a link that might be useful: toto clayton airbath.

I just had a Mirabelle Bradenton 60x32 alcove tub installed on very short notice; had to choose from what I could get shipped that week. Fortunately, these were displayed at several local Ferguson showroom/stores so I could try them out first (Mirabelle is an exclusive Ferguson house brand in the US; this one is made by Clarke though I don't know if they all are). I like it alot; it's a very comfortable, *deep* tub and thanks to the thin sidewalls, it's wider than most inside as well, despite the thin armrests. The backrest is sloped enough to be comfortable but not so much as to steal showering space. We just used a simple Watts overflow from Lowes held in place with a single screw; it can be detached, reinstalled upside down with the drain slot facing upward rather than at the bottom, and you get two inches of added depth that way. American Standard sells priceier replacement "deep soak" overflows that are designed to look good with the drain slot near the top. Anyway, my only complaints with the tub are that they could have made it an inch or two longer at the drain end (not a problem for you it sounds like) and the armrest is a bit higher than I'd prefer - it is at a good height to use whilst sitting up rather than lying down in the water. This is designed for a single bather, but two could squeeze in if in the same direction both on your side, if you're reasonbly small. It would be a tight fit but may suffice for occasional use. There's definitely more room inside than most tubs with the same exterior length and width. As for whether 2 can fit in a 34"w tub; usually not unless it's a single-walled freestanding tub which is almost as wide on the inside as out, or is very long so you can stretch out or sit across from each other. Kohler makes a "Tea for Two" 60"x32" alcove tub designed billed as the only 5-foot replacement alcove tub that can accommodate two people, but that's a stretch; those who've installed them say to better plan on one at a time, name unwithstanding. I've found some 36" wide tubs that will fit two comfortably, both side by side or at opposite ends; 66" or especially 72" lengths help alot here, as do double-ended designs that place the faucetry in the center, but for both facing the same way an end-drain tub can work too, and they have the benefit of more foot room at the bottom of the tub. An apron is a panel found on some alcove tubs that negates the need for a wall of tile or other material on the outside of the exposed tub wall. It's often built in, but sometimes an extra-cost option (espcially with whirlpools and air tubs). Some drop-in tubs have optional aprons as well as optional tile-in moldings. Here's an example of a tub with a front apron:

Is you current tub/shower combo in an alcove? If your bathtub is enclosed in an alcove and has a surround of tile or other material and you measured from one end to the other, you need to add at least an inch to your measurement for each wall you encounter. When my son first measured his tub area he thought it was 28x58 but when the contractor measured it he said that the rough in measurements would be for 30x60 tub/shower. You may want to recheck your measurements. My son ended up using Kohler's 30x60 cast iron shower pan. It is designed to replace a standard tub. He did you glass doors on his new shower. He would have like to use a hinged door but had to go with sliders because he could not change the location of the valves and he wanted to be able to turn on the shower without getting into it first. My son falls into the big and tall category and did notice that the shower area seemed slightly smaller with the glass than with a shower curtain. But even with that he prefers having the glass doors. Here is a not quite finished picture of his shower with Kohler's Salient shower pan.