Where I may have some uniqueness is that I have an extremely strongly skill set in Excel and VBA.

These are the types of Tenants you have to stay on top of so that you don't end up with a loss in rent due to eviction.However, it sounds like you have a somewhat unique Tenant in that she does not appear to be struggling financially, but rather is just forgetful or slightly irresponsible when it comes to deadlines.I liked what @Tyler Gibson suggested to have you pre-print the late notices in advance and have them ready to just drop in the mail. 

The end result was a gorgeous property that was warm, stylish, and unique and immediately attracted the right buyer.

It sounds very unique, which is cool, but may lead to problems with finding similar properties.

There are so many software AppFolio, Propertyware, Buildium, RentManager all have their unique features.

Those membership fees vary from a flat-rate to per unit.Each have unique offerings but a lot of similarities.  

My background is a building inspector so my construction, code knowledge and credit score was a very unique skill.  

@Margot Baldwin It seems that both of you and your husband are in a great financial shape to have a comfortable retirement, however, to answer your question, I would suggest to find a financial professional who understands your unique situation, and help you plan your retirement properly, and your estate planning needs.

There are numerous options today; each have their own unique features but also similarities.Besides partial payments, what other features are important to you? 

Each tenant has a unique rent amount, so even if the teller does not make a note I know whose rent is coming in.If someone has your account number, they MAY NOT withdraw from your account (unless your bank does not have any security measures in place).I have a separate bank account for each building that tenants deposit into each month and I typically have a large balance in them to pay taxes, debt service and other monthly expenses, and I don't have any worries about those accounts being drained by some unscrupulous tenant.