Designing Kitchens and Bathrooms - How Far to Extend Bathtub Tile Job?

I'm installing a standard 5' tub that's 32" wide. It's going to sit in an alcove of sorts. The front of the tub will be on a wall that's the whole width of the bathroom, while the wall behind the tub will only come out 48" then turn.

The only walls of this room that will be tiled will be around the tub, and my first thought was to tile out only to the edge of the tub. That is out 32". I'll be going all the way to the ceiling.

But then I wondered if it's more standard to extend the tile out beyond the tub a bit.

Is there a standard way of doing this? The one part that might be aesthetically challenging would be the 48" wall. If I tile out past the tub, say to 36", then there will be just a one foot strip untiled.

Any thoughts from the design standpoint of a tile job?

I like to take it out past the tub edge enough that it goes past the shower curtain. This is only about three inches and helps keep water off the wall at the point the tile ends. I usually accomplish that with bull nose pieces.

Same here. Extend the tile past the tub at least the width of the bullnose tile.

To continue this line of questioning...
If I'm in the same situation regarding one row of bullnose tiles past the tub, how do I best install the backing? I'm at bare studs now and I'm going to use 1/2" hardibacker, but how to I transition to 1/2" (green?) sheetrock? Where should the seam lie?

A rule of thumb - if the joint between where the hardi ends and the drywall begins will be tiled over, it gets taped and mudded with thinset. If the joint will be painted over, then tape and drywall joint compound. If you havent yet put up the board, the ideal situation is to have the joints just short of where the tile will end. Tape and mud with thinset, and the bullnose tile will cover the joint. You may need to add some framing to support the edges where the drywall and cement board meet if theres not already a stud there. The greenboard is a waste of money. For areas that will be outside the shower and not subject to direct stream of water, regular drywall will due. The greenboard is more expensive and is really no better than the drywall.