In general, I am a fan of "going all the way up", whether it be cabinets, or tile.

In your case, however, I think the second mock-up looks better and your instinct about it looking a teensy bit stange to have that tile above the curtain (and nowhere else) is correct.

Since you are putting up crown moulding I would stop it at the lower point on the wall.

I'm generally a fan of the lower stop on tub/shower combos, but I actually like it going all the way up in your mock-up.

I'd do it behind the toilet. (MUCH easier to clean off the overspray.) and take it all the way up.

Since you're doing crown, I would stop. I like that mock-up best.

We stopped... we had other issues to deal with, and an odd layout, but I think I now prefer it over taking it to the ceiling.

Here is a link that might be useful: Our DIY bathroom.

We tiled all the way up with white large tiles and mosaic on the tub wall. This was a DYI project.

I always tile the ceiling as well. If not, here's what can happen.