I own several rental properties and my experience has been that a good long-term tenant is worth their weight in gold. I would follow Margaret's advice with this person.
Normal and desirable vacancy rates in large rental buildings are 5-10% per year, and in theory a landlord's rental rate should maintain that kind of vacancy--the higher the rent, the more turnover in tenants you will have.
But for a small scale landlord like me (and perhaps you), who doesn't have enough units to benefit from a formula like that, every time a tenant leaves it's an expense. It's not just the lost rent, advertising (or in my case, property manager advertising expense), it's also the complete repainting, floor maintenance, etc. required.
Some tenants take very good care of your property but many do not. "Normal wear and tear" is not something you can legally take out of the security deposit, but there's quite a range as to what that means. A gentle tenant is worth more than one who is hard on everything.
Also, if your tenant does not let you know about small maintenance issues for fear of bothering you, that is good, but you should inspect the property once a year with the tenant and ask about small repairs and things not quite right. Attending to small things will save you money in the long run.
One last thing to ponder: It's difficult to evict people in New York, which has the effect I think of keeping rents a little lower than they would be otherwise. In other parts of New York State, if somebody doesn't pay rent, you can have them out in a month. In NYC it's very difficult and takes many more months, which has the effect of making good tenants more valuable.
Karla Harby, VP
Charles Rutenberg Realty