The only bear country I've camped in has been black bear country. I'm too scared to camp where brown, grizly, or polar bears live. I think it's important to remember that
we hiked all our gear up to be in
their home. If a bear came into my house to sleep the night, I'd make sure it left. Fortunately, black bears are more considerate than we are.
AF Canyon, the Rubicon, Yosemite, the Sierra Nevadas, Uintas, Payson Lakes, are all black bear country. Fortunately, black bears are, for the most part, not interested in humans at all. They eat berries and small animals, not humans. If they hear your voice, they run away. We saw one about 100 feet away at Dutchman Flat a few years back, and we walked towards it to get a better look, and it took off running. A lot of hikers tie bells around their pack so bears can hear them coming, and the bears will scamper away. You can also talk while hiking so they can hear your voice. If they hear your voice, they'll usually flee the area.
I don't know how bells on a tent would help.
Since bears aren't just lurking in the woods, waiting to attack me, I don't keep bear spray on my person. My wife does though. She puts it in the side pocket of her pack. If she gets worried that there might be animals nearby, she'll take it out and carry it in her hand for a few minutes until she feels the threat is gone. It makes her feel safe, and that's important to me. When I'm sleeping, I have it right near my head, ready for instant action if I need it. Having a dog also really helps us feel safe, as he will alert us to any nearby camp intruder.
In my mind, Black Bear safety here in Utah really comes down to food. They don't want you, they just want your food. Keep a clean camp. Don't throw unwanted food in the fire, and don't spill it around camp. Prepare food away from the area where you'll be sleeping. Make sure you don't smell like bacon when you go to bed. Store food AWAY from your tent. Put it in a stuff sack and throw it up in a tree so they can't get it. Bears aren't the only critters interested in your food, so that's a good practice anyway. Even if you're leaving the campsite for the night, don't leave food around. Inevitably, there will be more campers in the area soon, and they won't appreciate you attracting bears to the area. In Yosemite, you could feed black bears out of your hand (you should never do this) because they're so accustomed to humans leaving food around. They've learned that if they come into campsites, they'll have easy access to food. If we can remove any enticing for a bear to come into our camp for food in the beginning, we won't have to deal with bears coming to camp expecting to be fed. They simply won't come.
I was pretty worried about bears and mountain lions on my trip to Lake Hardy, and I didn't sleep all night. We didn't bring enough paracord to hang a bear bag from a tree, so we set all our food out on a rock about 200' from camp. it was all still there in the morning, and we didn't see any evidence of animals, but it wasn't a good idea and I don't recommend it. We burned all our trash and food-prep materail about 200' away from camp so we didn't attract critters. Then again, maybe it was my snoring that kept them away.
Here are some more links to bear safety:
http://wildlife.utah.gov/dwr/learn-more/bear-safety.html
http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsem_035131.pdf
http://www.fs.usda.gov/detail/uwcnf/learning/safety-ethics/?cid=STELPRDB5085986