Tavern 245 is one of our regular happy hour spots. Modern vibe to it but the chairs/sofas are still pretty comfortable. And as one expects in a Pgh bar, TV's so you can watch sports. Specials are good, the bartenders are friendly and while it gets busy for happy hour, it's not too crowded. It may feel a little hazardous getting down the stairs when you've had one too many but I haven't heard any reports of accidents so it's really not that bad;)
For lunch, I've only been once; got a burger which was pretty good. Prices are very decent for downtown. Make sure to get here a little early for lunch as the service is a little slow once they get busy (a sentiment also confirmed by coworkers who've gone more often). I certainly wouldn't mind coming back for lunch again.