Well I'm happy they chose not to decline the application on the grounds of not including the letter from my sponsor. I guess they know that it was a simple mistake (I honestly didn't read anywhere it was a requirement, in hindsight it makes sense). Me and my wife have been married in the US for nearly 5 years.
I've provided 6 months of bank account activity showing both mine and her direct deposits from our employer, her bank statements from UK, our most recent tax returns, a letter of accommodation from her sister who has a 5 bedroom house, original birth certificates, passports, my college diploma, the deed to our house, etc. I'm sure they realize it was an honest mistake, and fortunately I've been given another opportunity to submit the paperwork.
I appreciate the example sponsorship letter! Sometimes the whole process can get overwhelming. Part of the reason I misunderstood how to get priority service. Oddly enough, this seems more stressful than when we got my wife's greencard. ARGH!