Also, my local plumbing supply house is Kohler and they don't carry Toto. I did get my valves locally for Kohler (using the GC/plumber's discount for what it was NOT worth!) for my kohler fixtures, but for my "cheap bathroom" I used Faucet Direct (highly recommend them) and when you select trim, they "suggest" the correct valve(s). I doubt your GC can beat their prices, free shipping, and no local sales tax. Faucet Direct gave me better service, so I felt absolutely no guilt not buying local. In fact, every online retailer I dealt with seemed to care about me as customer when all I was was an order and credit card. They were fabulous. My local supply house? No interest in pleasing me at all.

The problem is that the "pretty" has to match the "utilitarian". THe trim has to match the valves inside the wall or it won't work correctly. There's nothing wrong with you using a X brand toilet, Y brand sink, and Z brand lavatory faucet (if you like how they match). Those come complete with the needed accessories to install them. Your tub and shower faucets aren't ordered that way. When you order your pretty stuff, you have to order the right valve for behind the wall that the pretty stuff works with. And, it's not the easiest thing in the world to understand how to design a shower with multiple sprays and valves. You really have to know what you're doing to not order the wrong thing and get stuck with not being able to return a $600 Roman tub faucet with side spray that you got the wrong valve for. You just wiped out any bargain hunts right there.

Part of what you pay a professional for is the knowledge he brings to the job. Let him design the showers and tubs to your specification and then let him order what is needed. You may end up paying a little more, but then you also have the actual install warrantied. If you provide the fixtures, you are the one that deals with the warranty issues. If that Moen shower valve starts leaking behind the wall, if the plumber supplied it, he's there fixing it. If you supplied it, he might be there fixing it, but it's you that's paying the labor to fix it (and the ripped out tile if you don't have an access panel) and you that has to send the defective part back to the manufacturer and wait on a new part to be installed.

The valve behind the wall has to work with the trim in front of it. Read the specs sheets to confirm.

You can use any brand shower head on the pipe that comes out of the wall; they all screw in the same way (assuming you choose the right diameter pipe and the pipe is far enough from the wall, etc.)

Here's how I did it: I did a bunch of research and printed out the spec sheets for what I wanted and thought would work. Then I paid my plumber for an hour consultation to see if I was correct. (Among other things, I'm replacing a valve in a 3rd story shower that I am not retiling-he only has access to the plumbing through one hole in the sheetrock. So it was not straightforward.) He even verified which Grohe valves to buy.

Now I am free to order what I want. The plumber's company charges full retail prices and I can buy them online for 40% off. (I called their office and verified, that "oh no, they don't match prices" as if that was the most ridiculous concept ever.) Even if I make a mistake or two and have to pay him travel time to come back, I'm still saving a lot of money.

Excellent information here. I was kind of afraid about the complications of mixing and matching the utilitarian bits with the pretty bits. I'm loathe to pay retail or "plumber's discount" prices for some of these fixtures though when the faucetdirect.com price (thanks for reinforcing my thoughts on going with them, grlswprls) is going to be significantly less. If it's just one fixture it's not a big deal, but when you're outfitting an entire bathroom, that money adds up.

Perhaps I'll propose what marie_louise did ... pay the plumber for a consultation to make sure that I get all the right pieces.

As for mixing brands in the shower, honestly, I don't like any of the Kohler shower fixtures other than the Flipside handheld (which will be our only water source). I can justify the added expense (over another brand) for some fixtures (like the Kohler Margaux faucet) because I really like them, but it's tough for me to shell out $50 or more extra for a fixture I don't even like.

However, it sounds like that may be creating more work than it's worth so perhaps it's best to keep the fixtures limited to one brand in the shower. After all, at this point $50 one way or the other doesn't much matter. I'm not budging on the toilet though ... the plumber will just have to deal with that!

I'm not a big believer in the theory that everything has to come from the same line, so I'm just trying to choose fixtures that relate well to each other and keeping them all chrome, since unlike nickel finishes, chrome is pretty much standard across brands.

OF COURSE you can mix and match -- makes absolutely NO difference. Kohler body sprays with Moen hand spray with Grohe rain shower with Hansgrohe thermostatic valve and volume controls! (or any other combination)

Keep in mind that some finishes are not identical across companies -- polished chrome is safest.

That said -- if for instance you select a Hansgrohe thermo valve -- you MUST use the matching Hansgrohe valve, which is the part in the wall you can't see (you can't, say, use a Kohler valve with it).

In terms of the thermo valve -- if you have multiple shower heads, you should think about getting a 3/4" valve and making sure the supply lines are 3/4" as well so you have adequate volume of water.

Good luck with your bath!

Pete

I spent $5K on trim and fixtures for 3 baths and partially for the kitchen at Faucet Direct and I had the stuff within in the week. The local plumbing supply place couldn't do that either.

I did go with chrome though. That is one finish that is universal.

We did quite a bit of research at our local plumbing supply stores, learning what bits we needed/wanted. They were very helpful, as they should be, optimistic of an eventual sale.
Then we started our pricing research.
We checked both online sources (including eBay) and we were able to get Pacific Sales (a Best Buy company we have here locally) to match the lowest online price we had - minus one dollar. If they hadn't matched the price, we felt comfortable enough with the research we did on the exact parts we needed and would have ordered them online.
It's true that you can mix/match shower heads and hand helds, but the "pretty bits" that divert and turn on the water have to match with the rough valves (ugly bits) behind the wall.
Even though we used all Moen trim, since the parts are made from different types of metals, the "brushed nickel" looks slightly different on different pieces. So I wouldn't worry too much about slight differences in finish.