Each time she beat me to our appointed time, and I am seldom if ever late. 

Oh, one more thing, instead of asking her to confirm receipt of the letter, which she may stubbornly refuse to do, just say she should contact you to work out a mutually acceptable appointment for when you go back in to inspect. 

You should be unreachable until the day before to arrange your walkthrough appointment and key-collection time.

Pick your battles.I won't even get involved in the call out, I'll pass the tenant number to my contractor and they will make a suitable time for an appointment.

EMOTIONS RUN HIGH and this is why a court appointed official called a Bailiff will go out to the home and remove the tenant from the premises and Not YOU!

DH and I both work, and he's out of town for the next few days anyway, so rather than making 15+ individual appointments, we decided to basically just open it up for a few hours Friday after work, and I've been telling people to come, have a look, and then fill out the application if they are interested, but I'm honestly totally blown away by the # of responses, and my phone is still ringing.  

How about, sending her a letter with a couple of appointment options to choose from in the next week.  

I will offer them a well appointed and kept home at a reasonable price all day long.

I suggest you go to their office and make an appointment to talk to them about what you can do, including if you need a new contract, or have to honor the current one, etc.Los Angeles County Section 8 pamphlet on payment standards, etc.The HUD contract with the landlord, usually includes that the landlord can't evict the tenant except for cause.  

In addition with the number of tenants I have it would take me a week to call, make appointment and meet with every one to collect rent.