Dromore West Workhouse
There is a workhouse in Dromore West in west Sligo which is well preserved but is privately owned and not open to the public. But if you enquire locally and have connections with the area you may be able to visit it. You can certainly see it externally and it is a fine example.
The others I know of are Portumna, Co. Galway and Donoughmore, Co. Laois.