While you have trademark rights through use ("First in use is first in right"), there are several advantages to registering a trademark with the US Trademark Office:
1. Once a mark is registered (principal register), there is a presumption of trademark ownership and validity in any subsequent litigation involving the trademark.
2. Trademark registration also creates what is called "actual notice" or "constructive notice," which informs all parties that the trademark is the exclusive property of the trademark owner, and which also allows the owner to recover profits or damages for trademark infringement.
3. Judicial remedies are broader. A trademark owner can be awarded treble damages against an infringer whose infringement was deemed to be "willful". In addition, there is the possibility that the court would award attorney fees in exceptional cases where the infringement was deemed malicious.
4. Registration (principal register) usually provides the trademark owner with rights in the mark for a larger geographical area (i.e. nationwide) than is otherwise possible.
5. The scope of protection for a federally registered mark is usually much broader in that it encompasses related products or services, rather than a specific product or service.
6. Your mark may become "incontestable" after 5 years.
You should look for an experienced trademark attorney who does work on a fixed basis. An example of this is http://BealBusinessLaw.com/fixedfees.htm under "Intellectual Property".
I do not know all the facts of your case, and I do not legally represent you. Although I strive to make sure the information I provide is generally accurate and useful, you should promptly consult a lawyer who can learn the details of your case more completely, to ensure that the information I provide, and your interpretation of it, is appropriate to your particular situation.
If you would like to discuss this matter further in a more private forum, please feel free to contact me directly at the email address provided by my blog or through my firm’s website located at BealBusinessLaw.com.
Attorney Beal has provided some excellent advice, and you're smart to hire a lawyer to help you get your trademark. About 1/2 of all trademark applications are rejected, and I bet that many if not most of those are done without the benefit of a lawyer.
The fact that you've been using the mark for 10 years (and you haven't mentioned anyone contesting your TM in that time), may mean that you'll have an easy time with this application, but maybe not, you never know what the USPTO is going to come back with.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.