As a birthmom, I have to say I agree with Nelson. I think a 2-3 page letter is best. You do not want to make it
too long, because sometimes a pbmom has to go through many "dear bmom letters" before she finds "the one."
I also prefer letters/profiles/hoping-to-adopt sites that give you a brief overview of the couple, before having to read their entire profile. By overview, I mean, a small paragraph or outline that only takes a minute to glance at telling basic info like your ages, how long you have been married, occupations, etc. This way, if a pbmom is looking for certain "qualifications" (for lack of a better term) she is able to glance first and see if you meet her desires before reading a lengthy letter!
~ Coley