What do you do about tourists who keep walking into your field of view as you are framing a shot? There is little more to do than wait it out. If there are only one or two and they are lingering you can ask if they would mind moving (over there) for a couple of minutes while you compete your shot(s).
I often watch for small groups of tourists - and shoot them - under the right circumstances. It may be good for business, which I wrote about here: CLICKY.