I'm getting ready to remodel a bathroom and it'll involve a few sub-projects:
installing bathroom fan/light/vent (for the first time - which will require roof vent)
replacing drywall on walls (possibly on ceiling too)
replacing vanity and sink fixtures
replacing lighting fixtures
My original plan was to demolish everything... then start on the subfloor... and then work on electrical while the walls are open. I don't know where things like painting fall in though... because I don't want to paint walls too early but it might be difficult to paint around fixtures once they're in.
I have done quite a few bathrooms from start to finish. You don't always have to do things in a certain order but I can tell you generally how to do things the easiest.
You start with your shower pan and/or tub in the bathroom. These are specific sizes. You don't want to have to find something that fits exactly what you need - unless you plan on making your own cement based pan.
Make sure framing fits your choice of tub/shower. If not adjust/make walls.
Start with the subfloor for the tub/shower area.
Do exit plumbing and install tub/shower.
Make sure that you have bought vanity and any other fixed pieces (mirrors/medicine cabinets/whatever) for the bathroom at this point. It is important to know the height of new vanity, height of backsplash pieces and other things so that electric/plumbing considerations can be taken. For instance with taller vanity you might need to bump the GFCIs up a few inches too. If you have a vanity with drawers sometimes your exit plumbing hangs to one side or your faucet water needs to come from the middle.
Do rough-in for plumbing.
Do rough-in for electric. Also if you have venting that runs to fans I would do this here.
Do the rest of your subfloor if needed. Your tub/shower subfloor is a different world. Different needs and the rest of the floor probably has to match up with the next room. For instance you don't backer board under a shower pan - but would for tile in rest of the room.
Lay your tile. Everyone has their opinion on aesthetics. But I will say the easier - and it looks good too - way to do it is to start opposite your vanity wall. Get most of your cuts hidden under the vanity. Also try to plan your toilet across two tiles if using large tiles.
Hang drywall. Mud and tape. Also if you are tiling shower - then hang your backboard and waterproofing at this point. Backerboard and drywall should be done at same time because they need to meet at pretty much the same depth.
Prime and paint. I would redgard the shower area after priming the other walls if it needs it.
Tile shower area.
Install lighting, cap off the rest of the electric.
Install vanity, hook up sink to drain, install faucet.
Put up mirror, medicine cabinet, shower trim, all that stuff.
Install Toilet - you can do this much sooner if you need a place to go but I leave it close to last because I have chipped a few toilets, dropping whatever.
Put in trim around room.
Install any kind of glass enclosure/doors/panels for shower/tub if needed.
Well there's the way it's supposed to go and then there's the way it usually goes. You can plan it out all you want but once you get into the thick of it the plan often has to change. In the most general terms a remodel has 9 steps. Actually 9 and a half: before step one make sure to order all of your parts/pieces that can't be had locally. Get them in before you start demo. I once had to wait 6 weeks for a Jacuzzi tub which was a problem since I had already torn some poor guy's bathroom down to the studs.
Demo. Tear out everything that's going, open all the walls that need to be touched, etc. In a bid I like to add to this step a process I call "Getting back to Zero" which is the process of fixing all the stuff you didn't know was wrong before you opened the walls. There might be mold, missing substructure (I once opened a floor that had no joists, NO joists!) basically you need to fix the unknown unknowns before you can move forward.
Framing (if any). Reframe anything that needs it, add studs and blocking for grab bars etc. To this you can add laying subfloor if there's nothing running through the floor.
Rough-in. Rough in plumbing, electrical, anything that gets covered by drywall. If you're going to pull permits now is the time to call your inspector (actually that time was a couple weeks ago but this is your last chance).
Wall/Floor Coverings w/ variable. Time to put down your subfloor, hang your drywall, and set your wall tile underlayment if applicable in that order. The variable is if you need to do any concrete work (floor leveling, shower pan, etc) do that before the drywall.
Wet work. Mud, tape, texture, and paint. Pretty self explanatory just try to work from the ceiling down.
Hard Surfaces. Set your underlayment, tile, and grout. Or substitute for whatever floor covering you've chosen.
Fixtures/Cabinets/Trim. This includes outlet receptacles, light switches, fans, anything that bolts on.
Touch up. caulking, nail heads in the trim, that sort of thing.
Bubble bath. Pour your wife a bubble bath so she can enjoy the new bathroom, by this point you'll probably need some brownie points.
Keep in mind there are a million reasons you'll need to deviate from this schedule but essentially your just trying to keep from burying areas you still need to work on and keeping the mess from one task off the other areas if possible. Good Luck!