Lindsay Powell, who recommends Travel in the Ancient World by Lionel Casson which I listed yesterday, also likes Life and Leisure in Ancient Rome by J.P.V.D. Balsdon, London: The Bodley Head, 1969, which can be had very cheaply on the used book market in the paperback edition of 2004 by Phoenix Press.
There is also Pagan Holiday: On the Trail of Ancient Roman Tourists (originally published as "Route 66 A.D.") by Tony Perrotett.