So even though some the original creditors settled up or sold off the accounts, at this point the basic GW letter is all I can do?
Also, is it the standard procedure for GW letters to simply mail them to the account shown on the credit report?
Settled is paid. If they sold the accounts and you paid the CA you can still ask for a GW because even though they sold the debt their TL is still reporting. And the debt was paid to the CA.
Yes, mail to the address on your CR.
What do you write in the GW letters? Does anyone have success with calling the companies and requesting? Or, is writing better?
You can. Yes, there has been success by calling.