The contributions people make to nonprofits and charitable institutions vary in terms of amount. Not all donors are equal therefore you have to recognize them in different ways. There has to be a difference in how a donor who donated a quarter of a million dollars is feted when compared to those who donated $10. This does not at all mean that the ones who contribute the small amount are inferior in any way, but the disparity in the level of contribution requires you to be tactful. The best way to deal with this situation is by creating a hierarchy of donor recognition.
The easiest way to do this is setting a benchmark. You can have a threshold and only the donors who contribute beyond it will have their names listed on the donor recognition walls. Or, you could have separate categories for the major and minor donors and their names will be written as such on the donor wall. It is up to you to decide whether you want to categorize the donors or will simply go by the alphabetical order when adding their names to the donor wall.
Moreover, you also have to work out the number of categories that you want. It depends on the donations your organization receives on a regular basis. You will have an idea of the variation that is commonly seen. For instance, if the contributions you receive range from $10 to $1000, you don't need categories at all. However, if the range spans from $100 to $1 million, you definitely have to separate the donors.
One thing you do need to keep in mind is whether there are any donors who have pledged a certain amount and are going to contribute it regularly over a period of time. There are examples where people contribute a certain sum, let's say $5000, for five years. Their total contribution is $25,000 but in the given year, they have contributed only $5000. So, which category will they belong to? And will there be a separate category for recurring donors? This is something you need to figure out.
Creating a hierarchy of donor recognition makes it easier for you to arrange the names on a donor wall. Moreover, you have a clear idea of whose name is to go on the donor wall and whose isn't. The hierarchy needn't necessarily apply to the donor wall only. Any other donor recognition initiatives you are planning can fete the donors based on the categories you put them in.