If I understand the situation, the normal brushes on an agitator simply won't reach down into the deep crevices. Right? So you're dependent on airflow to pull up any dirt on the grout. I can attest that the airflow on my oldish Dyson DC-07 is pretty impressive; it seems to be far more than that of my other vacuum, a Rainbow. Whether that's more than some other brands, I can't say.

Wouldn't a broom work?

a spanish vacuum

If you are not familiar, the grout in this particular style tile is 1?"-2" wide and caves down deep so the gap between tiles is very large. I've tried the Swivel Sweeper as a cheap alternative to a vacuum but it doesn't do as well as it did in my previous house on the linoleum. Most uprights I've ever used didn't do good on hard floors so I am hesitant to buy one, even a Dyson (even though I've never used a Dyson before). I would think a canister vacuum would do the trick however I have had a hell of a time finding a good, inexpensive canister. I do not want to spend very much as I will only need it for a short amount of time (couple years) and then will be leaving it and it's floors behind.

Thnaks!