Well in terms of out there visuals and combat sequences, Macross Zero has what I think are the most absolutely phenomenal CGI combat sequences I've ever seen. Seriously, the first time a Variable fighter transforms they devote something like a whole 30-60 seconds on it just to showcase how smooth, cool and detailed that sequence is. And beyond episode 1, the combat sequences generally get even more explosive. Although the plot could have used a bit of work, it's still probably not as mindless as you're looking for. Nevertheless, it is definitely a visual spectacle
After that, Hellsing is pretty audacious in its fight scenes and gore. Anyone who's seen episodes 5-6 knows that. Here's a hint, when the episode preview says there's going to be a rain of blood at the Hellsing Manor, they're going to frigging well give you a rain of blood in the Hellsing Manor :mrgreen: . No real plot to speak of, but it'll keep you watching in between the action. Sounds like just the thing you're looking for, it's all style and action.
Can't really think of any others I've seen that showcase a large amount of spectacle, at least not without a heavy-duty plot generally besides it.