My wife got here 10 yrs ago with no permit. She has never been in trouble by law. We been married for 2 yrs but been together for 6 yrs. What kind of letters do I really need?
You are a living proof of what I have been saying all along on this forum: preparing and filing an inadmissibility waivers without a competent immigration attorney on board is not advisable and may hurt your chances of success. Listen to US Supreme Court's Justice Stevens in Padilla v. Kentucky (2010): "nothing is ever simple with immigration law— including the determination whether immigration law clearly makes a particular offense removable." Good luck.
First, be most careful when doing an I-601 (or I-601A) waiver application and be sure you are represented by a very good and capable attorney. To hear that you are filling out a waiver application is very problematic because many attorneys need to learn how to fill these out and seek a waiver so a non-attorney doing it is troubling. In any event, you need to seek counsel immediately because you may be filling out the wrong form. For example, depending on your circumstances you may be better advised to file out the provisional waiver (I-601A) which is coming out very soon. Whether you need the provisional waiver or the regular waiver (I-601) depends on your situation which an attorney can help you with. Furthermore, the mention of "letters" tells me you may not understand what kind of evidence you need to support your waiver application, and "letters" without more is not sufficient evidence. Seek an excellent immigration attorney with plenty of experience doing waiver cases.
Based on your question, it appears that you really need to work with an immigration attorney on this case. An I-601 application for a waiver involves some complications and needs to be handled with care and expertise by an experienced attorney in order to have the best chance of success. You do not provide much information in your question, so it is not clear exactly what the circumstances of your case involve. You really owe it to yourselves to hire an experienced immigration attorney to prepare and submit the required applications and accompanying documents, and to avoid bigger problems in the future.