You probably don’t have to worry about this. Most wood and tile floors are very hardy, enough so no vacuum will scratch them. Furthermore, most worthwhile vacuums come with rubber wheels, which is one extra layer of protection against scratches.
However, if your expensive tile floors sit near the soft end of the Mohs hardness scale, or your softwood floors are prone to scratches, your safest bet is to get a canister vacuum with a parquet floor tool. It has no wheels and no brush roller—just a straight suction tool with soft trim around the edges. This kind of tool is usually a toss-in with any high-end canister vacuum, and you can even buy configurations that come with only this tool.