I would just do the handheld on a bar, otherwise you will need to add extra plumbing and a diverter valve to accommodate the extra shower head (I am assuming you will keep the tub spout).

We just installed Kohler Bancroft fixtures in our shower. It is a master, and we splurged a bit to do multiple shower heads, but the Bancroft multiple-function head is a nice shower head on its own. There are a number of traditional-looking Kohler styles that come in brushed nickel.

If you match the finish between the sink and shower you will be fine. My sink faucets are the Kohler pinstripe, but the shower components are Bancroft. With brushed nickel you can probably even get away with different manufacturers for the sink and shower faucets without anyone noticing (especially a gaggle of boys).

I would select a good quality handheld shower on a bar, just like jrueter. One that is totally adjustable. I certainly wouldn't call it chintzy. (It was suggested by a designer for a $60K+ remodel for our small master bathroom. Grohe comes in all the finishes, and styles, as do others. See them at local plumbing shops, and hold them in your hands to decide which one is best for you. Usually you can interchange the various parts within a manufacturer. I believe the threads on the heads will go with just about any make of hose. Not sure about that. Unless you can view both the sink an the tub at once you don't need to worry about having all the finishes match. We tend to get obsessed about these things when we remodel, and in the larger scheme of things, it really doesn't matter. What you would probably notice is traditional v.s.contemporary. So I suppose style would be more noticeable rather than finishes...but not going from ORB to Chrome would look weird.

I wanted everything SQUARE in my bathroom, and I was able to find different mfgrs. who did chrome with square designs in just about everything from shower fixtures to towel bars.

Chrome always looks the same. Brushed nickel doesn't as I learned in my kitchen...but one would only notice looking closely and the items would have to be side by side. So don't worry about that.

Get what YOU like to look at. Mount that bar up high enough, ( they do come indifferent lengths) The boys really only care if it works, not how it looks.

-Babka

That's the setup I have in my alcove shower over tub. I don't think it looks chintzy at all. In fact, if I'd added a fixed shower head as well, it might look cluttered.

My shower hardware and sink faucet are all Grohe with chrome finish. My faucet and tub spout are one model and my handheld is slightly more contemporary in design but they all seem to work together.

We just did our hall bath and chose just a handheld for the shower/tub, no other shower head. It just seemed superfluous to us. We didn't choose a sliding bar, but in your case, I definitely would. Can you get a bar long enough so that at the bottom the youngest isn't getting drowned and the oldest can still stand under the spray?