Usually a trademark filing includes a boilerplate claim on obvious variations, and is writtent to be as broad as possible - it costs the same to submit an overbroad claim as a narrow one, and if the USPTO doesn't give you everything you ask for you haven't lost anything by trying.

Not a lawyer, you should consult one. Alternatively, just head over the to the USPTO and read some trademark filings, which will give you a feel for the process.