I had a lovely stay at the apartment above The Glens Centre. As someone who is a frequent visitor to Sligo this is an ideal base. The apartment can sleep 5 people between two bedrooms comfortably, and has a generously sized living room / kitchen area.
One thing to note is that the apartment does not have a washing machine or dryer but there are pay-as-you-go machines at the local petrol station down the road that do the trick.
Brendan was very helpful and responded promptly to any of my messages.