Lets put it this way-- it'd look a HELLUVA lot better than just caulking it at this point! :-) Go with the ceramic 1/4 rounds. They do make end caps for them, if you need em.

Just set the 1/4 round on the floor without any cement, and see how you like it. Depending on your personal taste and the style of your bathroom, you may or may not like it. At least you'll have a better idea how it strikes you within the context of the room. Personally, if it were my bathroom, I would hammer out the adjacent tiles and re-tile it up to the tub. Stuff that I've worked on around the house that I'm not happy with aesthetically just ends up annoying me to no end. I've redone a couple of projects in my house just because I didn't like the way it looked in the end.

What color is the tub? Bill Vincents idea of ceramic quarter round came to mind also. I was also thinking of a strip of thin marble, it might give it a custom look?

I had to laugh when studio mention the tear and redo...that's what I would do and, how many times have I had to do that on some of my projects!!!!