Ideally the grout lines would line up from the floor to the wall.

Practically speaking, it makes no difference. Mechanically speaking, it makes no difference. The only difference is with respect to aesthetics, and the only person who could really answer that correctly is you. (a lot of help I am! LOL) Either way, you should still be able to line up the floor and walls as the first poster suggested. Not absolutely necessary, but always a plus aesthetically speaking.

Just so you know, the tile are all lined up, beautifully, thanks to my talented workers. The niche is narrower but I decided that the illusion of space is better served by keeping the tile layout uniform. I suppose I will have to buy one of those wire hangers for around the showerhead, but as this is a guest shower, maybe it will be OK with out one.

Can you show pics?

It is still unfinished. No door yet, mirror not done, walls unpainted , not sure about the light fixture, no faucet or vanity top and not all the hardware. But otherwise, all done! ;) Do you just want to see the tile? This was taken with a flash only. The tile all matches; color is of course not accurate. This is to show the tile layout. And maybe you have to click on it to see how the wall and floor grout lines match. Hmm, nope, that doesn't work. I will post another in better light when complete.