There isn't much in the High Street anymore, Rory. It used to have the Crown and the Plough, but they have since been appropriated by a shoe shop or knocked down to build the Regent Arcade respectively. All there is really, is the Hogshead - which is horrible enough to walk past, much less walk into.
Montpellier area has always been great for pubs. A friend of mine bought a house near the Eagle Star tower because she would be able to crawl home after a night out in Monte.
If Luke wants to avoid O'Neill's but stay on the Promenade, he need only walk a bit further up to The Rotunda ("The Rot") or cross the road behind for the Montpellier Wine Bar, The Salisbury or The Courtyard.
Just further up the Suffolk Square area is brilliant for places to eat, as you have mentioned. The Spice Lodge is a decent one for those who like Indian food, although the best in town would be The Everest which is on the opposite side of town as you come in from the racecourse.