Just looking for some suggestions/input on an upcoming lens purchase. I shoot mostly sports photography and am looking for a decent walk-around lens to use and not always carry my bigger glass. Mix of indoor and outdoor stuff. Here are the two current contenders I am considering. Tamron 28-75mm f/2.8 IF ED DX Nikon 18-200mm f/3.5-5.6 AF-S VR The Tamron can be had for about $300 or so and the Nikon is looking around $600. Nikon has better range, but somewhat average reviews. Tamron has pretty good reviews and fast aperture but obviously not as much reach. I have an 18-70mm AF-S(non VR) and Sigma 70-200mm f/2.8 HSM (great, but big and heavy) Any suggestions?