The disused AIB is in Castletroy on the other side of the Dublin Road from The Hurlers bar and a bit out from the City Center. There was a robbery at this branch about 20 years ago where the thieves cut a hole in the roof over the weekend and lay in wait for Monday morning. AIB ended up building a new premises next door and left this building idle since then.
The Aire in Monaleen is very close to Castletroy, marginally more remote from the city center.
If the city center is your thing, options are thin but along the river on O'Callaghan Strand might be a decent balance between proximity to City Centre and not too much late night traffic.
Alternatively, you could try ringing somewhere like Woodfield House on the Ennis Road who have a relatively large and level car park to the rear of the premises, they may be open to overnighting either on a quid pro quo basis if you're eating/drinking there or maybe for a small charge, worst they can do is say no.