The 18-200mm is probably the best of a somewhat crowded APS-C superzoom field. Still, there are a lot of optical trade offs (distortion at the wide end, softness at max aperture throughout the range, and significant focus breathing (with a moderately close subject, when I tested it at 200mm, the 18-200mm frames like ~155mm on the 70-200 II). If you really believe you'll need the tele end, it's a decent option. Else, IMO the EF-S 15-85mm f/3.5-5.6 IS is probably the best one-lens travel solution (and with 15mm, you might even consider leaving the 11-16mm at home).
I'd skip the monopod. Instead, pick up a Gorillapod SLR-Zoom with the ballhead. It supports a gripped 7D with 17-55/2.8 well. Flexible, and would allow you to get in the picture (consider an RC-6 or RC-1 remote if you plan to do that).