Lots of people have the impression that Barri isn't an exciting place to visit. It can be with the right company.
Ponty is not at all posh. But an opportunity to see the South Wales valleys. If you are prepared to tolerate my driving (ask @netmouse), then there are other possibilities such as Big Pit; you can pretend to be a miner and go down an old coal mine, it's really cool), though swanking around the posh bits of Cardiff is cool too. Chroma should finish at 7 and I'd allow a good hour to get back into Cardiff centre.
I think my idea of fun and Sonia's may be quite different. I actually like naff tat.