Aluminium does under go oxidation, although it is white. Unlike iron oxidation which is orange. If the tile is designed for use in a wet area it is probably coated or anodised to prevent white oxidation. Check if cleaning will be a hassle (risk stripping the coating).

custom made vanity and wall cabinets should only be needed if you have awkward sizes as an off the shelf cabinet allows you to see and touch the product and is often much more economical than custom made ...unless you need to keep some special supplies (eg 24 pack of toilet rolls?) i suggest that a base cabinet need only be 450-500 deep which is plenty for folded towels and drawers and the in wall cabinet about 150mm deep (including most of the cabinet inside the wall and only a small frame for doors and mirrors projecting out) but the in wall cabinet may depend on existing wall studs and electrical wiring so think about what you would put inside the cabinets and only have enough inside cabinet space for those items (maximum toilet roll or fat shampoo bottle about 120mm...in small bathrooms the extra floor space makes drying and dresssing much more comfortable and by rotating the shower in the family bathroom there would be less wet floor in the walkway and if the vanity in the ensuite is away from the corner you can allow space for a handtowel and/or a very convenient space to hang a hair dryer ...

I would check with your builder about re-using second-hand products as it may have warranty implications for your new home. Be sure you understand about tiling lips for bathtubs as it will affect your placement, waterproofing and tiling. I would not re-use, but sell it on ebay and buy a new equivalent rather then spending money on re-enamelling and re-installing. Best of luck, Dr Retro of Dr Retro House Calls

Hi, unless you take a bath at least once a week I'd skip the tub. I'd rather enjoy a bigger walk in shower, which is also a lot safer than climbing into a tub to shower. If you have the space instead of a tub and shower I'd consider a double vanity to give you extra storage space. It's a little luxury you will come to enjoy when everyone is getting ready on the morning.