Adding giving levels to workflow criteria

It would be great (imo) if there was an option in Workflow designer to create a giving level when a donation is received, rather than just greater than, less than or equal to a donation amount. I was hoping to set up a workflow that would automatically create an action for a fundraiser to thank a donor, and who will do the thanking depends on the amount donated. I have as a second step that if the donor is assigned to a fundraiser, that fundraiser will do the thank you, but not all of the donors are assigned a fundraiser. My workaround right now is that I do not assign a criteria to the workflow, and then when a donation comes in, I assign the workflow to a fundraiser depending on the amount. However, that's a manual step in what is supposed to be an automated process Unless I am missing something? Support did not seem to think so …