I can see Sundays being a big thing for me, so a good roast, like what Mulligan's and Kavanagh's do.
You're close enough to 5 Lamps Brewery to be getting deliveries by hand so I'd suggest making a big thing of that: having it as the house beer, a tap for unique pilot brews, etc.
Outdoor space would be good but there may not be much you can do about that. Is the big hole next door on the Clanbrassil Street side part of the premises?