You might try the bathroom forum for construct questions, they are very helpful.
This forum is great when you have it finished and need to organize. LOL

Here is a link that might be useful: Bathrooms

You might get great advice over at that forum, or at the Remodeling forum--but I bet we can give you some advice even now.

(I hate to shoo people away when they get just here)

So, some thoughts to help you get started.

Projects like this can generate a lot of paperwork: notes about phone messages left for contractors; actual bids and contracts; printouts of stats for sinks, faucets, cabinets, tile; etc.

My experience from when I am organized at work is that I am better off if I create the place to put the paperwork BEFORE I generate it.

For my kitchen remodel, I got a big accordion file w/ several compartments, and labeled them by components, and one for "General contractor." I ended up combining some of them, and breaking one out to be its own. But my basic list (counter & sink (Corian, so together, faucet, cabinets & knobs (added later to the sam ecategory bcs I used the same pictures), floor, dishwasher, stove, microwve, etc.)

I also find that broad projects like this overwhelm me from time to time. I like to make a master list w/ broad categories (hire a GC; buy a sink; buy floor tile).

Then I put major subcategories under that. And I get a stickynote and stick it in the middle of the page w/ the heading: "TODAY I CAN..." I'll write something like "-call the Johnsons' GC for bid" and "-email livewireoak to ask @ her tile floor" That way I know I'm doing SOMETHING each day

As for the bathroom itself, here are some thoughts about it

*USE FRAMELESS CABINETS IF YOU CAN. The most horrible bathroom vanity cabinet I ever saw was my cousin's; they'd bought their home from the builder, and the framed cabinets he used had the widest stiles & rails I've ever seen--there was a wide rail between EVERY drawer. Plus, the drawer front had a big space between the edge and the drawer itself. So although she had 4 drawer fronts, there was very little storage; I think each drawer was something like 2 inches deep.

If you end up having to go framed (bcs that's what the affordable line of cabinetry is), at least try to get one w/ a slim of rails and stiles as you can.

*DO CUSTOM CABINETRY IF YOU CAN. Sometimes this can be surprisingly affordable (though sometimes not). Going custom will allow you to control how deep the drawers are (maybe you'd like one drawer that's definitely deep enough to stand the shaving cream up in). It might be easier to have drawers on one side, and a door on the other.

It's my experience that sink cabinets in general, and esp. in the bathroom, can be frustrating caverns of hard-to-use space. A custom guy could help you install shelving and drawers that work for you.

And going custom would allow you to use a reverse sink base, which puts a drawer across the bottom of the cabinets, and doors above. This lets you access the full depth at the bottom, underneath the plumbing.

*DECIDE WHAT YOU WANT TO STORE. Make a list, even of the obvious things (toothbrush, toothpaste), but also of the not-so-automatic things (cough syrup? mine is in the kitchen; first aid? I like kids to bleed on the easy-to-clean tile, and the light in the bathroom is better, so I keep it there).
Where will you want to reach to get it? First aid, for me, can go off to the side; I want the toothpaste front-and-center, ditto the aspirin.
Then make a list of the stuff you THINK you want there, or would like to have if it will fit (extra shampoo, visitors' towels, etc.)

I find that I prefer a shallow medicine cabinet. Almost nothign in there is deeper than 3"--the widest thing is the shaving-cream can. Most stuff is even smaller, which means it gets clustered together, and I knock the stuff in front off looking for the stuff in back. (usu. when the sink is full of water)

I also find I have a lot of tall skinny things--toothpaste, toothbrushes (which I don't like to have out in the open), hydrocortisone cream & other ointments, comb, razor). These are very hard to store in my medicine cabinet, yet that's where I want them.

If I could have any medicine cabinet I want, I'd have one w/ shallow storage on the back of the door--tall compartments I can drop those things into. And a shallow depth on the shelves inside the cabinet.

I also find that there are certain, ahem, items I like to be able to access while I'm seated on the toilet itself. A fresh roll of TP, other products. I've heard of people who had a tip-out compartment on the side of the vanity closest to the toilet. Or a cabinet sunk between the studs near the toilet. I staple-gunned some cut-down shoe pockets to the inside of the cabinet doors, so they swing out and over to me (doesn't work for TP, though).

And we can all tell what we like about our bathrooms, or what we wish we had (double sinks, etc.)

Here's mine: My DH will NOT enter the bathroom if someone is on the toilet, nor can I go in if he is. I wish we had a separate toilet compartment, so if he's taking a while, I can still brush my teeth.

We have an over-the-toilet cabinet. It creates great storage space (esp. since it's above the space-wasting back of the toilet itself). And it gives me an excuse to force everyone in the family to SHUT THE TOILET LID EVERY TIME. Because if they don't, stuff can fall in. (I don't love the risk that stuff can fall in, but let me tell you--everyone in my household shuts the lid! It also helps that if they didn't, the cat would drink out of the toilet, and that grosses them all out tremendously. One of those male-female problems avoided!)

I was also intrigued by the person who has the toothpaste in a tilt-out tray in her bathroom vanity.

Best of luck w/ your project!

We're doing our bathrooms one at a time. More of just an update in the master bath, and a complete overhaul in the guest and half bath.

The first thing I did was list a few things.

What do I NEED in my masterbath? In order of importance.
Like do you NEED a closet, or do you have one in your hall/bedroom that works for bathroom storage?? Etc.

What do I HATE in my current master bath? Toilet to far away? Cupboards not spacious enough?

Then lay out. Do you want the toilet as close as possible to the door? In its own area? Would it be more esthetically pleasing on the other side of the room? Shower and tub combo?? Separate? Shower beside the toilet? Other side of the room?

Would it be structurally feasible to place a hidden walk through closet between the two bathrooms, so you can share a large storage space between the two? Would you want to? (I've always wished I could! You only need one of everything then!)

Once you have all that done, work in what you want esthetically, too.

Like for us, we got rid of a bunch of drawers on the one vanity, and replaced them with wicker baskets on shelves. More practical for us, as well as more pleasing to the eye, for the look we went for.

It helps to make a scale model of the floor plan. Then make paper cutouts to size of a tub, toilet, closet, vanity (anything you're putting in there) and move them around over and over until you find what you're looking for. The bathroom forum and Renovation forums can help with these, if you're unsure of how to do them. They really are a great help!