Well, it's my understanding that once you trademark a name, it's yours. Period. No one else can use it in any way, shape or form. For this reason, it can be kind of difficult to get a name approved for trademark and why so often they are made-up words like Xitztron or something.
When you see a trademarked phrase like "Only the best!" you might notice that it's always presented as a logo...so the phrase is only trademarked as a logo. Does that make sense?
"also, the thing about trademark law that most people don't realize is that once you trademark a name, you're kinda responsible for policing it yourself."
Actually, that's not entirely true. You receive notifications from the registry office any time someone registers a trademark that appears similar to your own with a letter saying "If you find this application to be in conflict with your trademark, contact your lawyer." I get them all the time, like if someone registers "Sublime Seasonings" but I don't pursue it. I'm not exactly sure how this works, but I know that all applications for trademarks goes through a publication process where they are first reviewed for conflicts with existing trademarks.
If you're serious about getting a name trademarked, get a lawyer to do it for you. That way you ensure it is done properly. There are all types of ways you can mis-categorize your trademark, be out a bunch of money, etc. Expect to pay around $1200.
eta: I've said this before, and it varies legally from state to state, but you can use the "TM" symbol freely like you would a copyright symbol without actually registering. You can NOT however use the circled 'R' without actually having a registered trademark. TM means pending trademark, the circled 'R' means registered.