If your at the canyon though still want to catch the big game there is at least one option for this. Maswik lodge and cafeteria area has a sports bar with a large screen TV. Bright Angel has televisions though the bartender mentioned that at night there is a band that would play. El Tovar has a cocktail bar with regular size tv's. These places are each relaxing places to kick back after a day of hiking.
Dress Code: None that I know of.
Nightlife? Well, I believe that probably the more active NIGHTLIFE are deers and skunks around woods (be careful with the last ones!!!!!!). Remember this is a National Park, no disco, but maybe the best place to drink a beer is the Sport Bar next to Maswik Lodge. Also you can play pool!
Also you can watch TV (each 4 year the Olympic Games, cheer up! your country!). Anyway if you hiking you need sleep at least 8 hours. Don't forget it! This Sport Bar is also a good place to meet new people and maybe find somebody to hike the next day.
Beer is cheaper in the General Store. (Good advice if you drink too much!)
Dress Code: Nothing special. Only age! You must be 21 or older to access and drink alcohol. Sorry! If you're under 21...Also is beautiful see the Canyon by night....WOWWW!!!! Beatiful stars and Milky Way.
The Lodge has a nice Lounge Bar with Irish Red beer among other beers.
Otherwise it's the TV in your room.