For the cable run, you said that the distance is about 28ft to the TV. Is that 28 cable feet (including the direction it's going to be routed, corners, etc)? If it's under 30ft, I'd personally run a high quality HDMI cable as well as a handful of Ethernet at the same time. If the HDMI ever implodes on itself, you could easily convert the Ethernet to HDMI, or you could always use the Ethernet for other uses.
For the Kinect, Monoprice.com sells a variety of distance extension cables. For the Wii Sensor Bar, wireless is an option, although I've had spotty luck at that distance. I'd also say that ventilation is definitely a concern. You can use many types of fans or cooling units to circulate air. A passive vent cover somewhere to let air out of the closet might be a good call too.