Sketch the floor plan of your home’s upper level. Keep the bathroom in its present location, but study where you can expand it. See if there's a closet in an adjoining bedroom that can be used for an expanded bathroom. Or consider borrowing a foot of space from an adjoining bedroom. A larger bathroom on the second floor could increase your home's market value, especially if it is part of a master-bedroom suite.
Measure the room, along with any space you plan to borrow from another room, and use these dimensions to draw a new bath layout on graph paper. Make a one- or two-sink vanity the focal point of the room. See if you have enough room to put the toilet in a private or semi-private area. Decide whether you want the shower or bath-shower combo to be a pre-made unit or something more lavish and custom. If you're going for a lavish look, this is a good time to browse the tile offerings at your home-improvement store.
Prepare to gut the room back to the studs, including ceiling drywall. Rent a dumpster to hold trash. Turn off electricity, as well as water to the room. Transfer needed toiletries and towels to a downstairs bathroom. Gently pry loose the old shower, bath and vanity from the wall studs, using a crowbar. Remove the old toilet and drywall, and pull up flooring.
Build back the room's components from the ceiling down. Run new wiring and plumbing while the walls are open. Use moisture-resistant drywall to finish the ceiling and walls. Install recessed lighting in the ceiling, and replace the fan vent. Install crown molding around the ceiling for an even more elegant look.
Add your main fixtures. Use high-end fixtures if your budget accommodates these expenditures. Base your choices on the style you're going for. White complements a contemporary decor, while antique styles complement traditional and Mediterranean decor. Add the shower and bath, and tile these areas if you're not using pre-made units. Install the vanity, along with wall mirror materials and lighting sconces. Seat the toilet with a wax ring.
Paint the room. If this is a master suite, create a space that looks like a retreat, instead of a family bathroom. Consider spa-like amenities such as heated towel racks. Choose paint colors based on the look you're going for. White creates a clean, spa-like look, while warmer colors have a cozy, relaxed feel. Install window treatments. Plantation blinds can look especially attractive in a bathroom.
Create a high-end look for the floor. Buy tile with texture to keep the floor from being slippery when you step out of the shower or tub. Put in new baseboards, and add your accessories.