From my incredibly cool resident friend, who shall also be at the show tomorrow.
best bet is to go to the area nearby called Channelside and go to one of the restaurants in there. There are a couple of different types of food to choose from. Unfortunately, there isn’t all that much in the way of nightlife in Downtown Tampa unless you head over to Channelside or Ybor City, and with them going to the concert, Channelside is their best bet. They may even be able to hop the trolley car that runs down in that area to Channelside and back up somewhere close to the St. Pete Times Forum for the show. The concierge could probably help them a little bit more with the specifics on that.
Most of my knowledge of nice places to go for dinner are a little further, closer to where I live, though the cab ride wouldn’t be a whole lot of money (it’s not that far of a distance, plus that sort of stuff doesn’t cost as much over here).
If they have the time, and are willing to take a 15-20 minute (tops) cab ride, here are some places they might consider:
(Might not be able to get in on this short of notice, it’s the nicest-and oldest-steak house here in the area)
(The spin off of the original that isn’t as “traditional” as the original)
(My favorite little Italian place in the area. Looks very upscale, but is casual. It is very reasonably priced with good food. I’ve been told the wine list is pretty nice as well, though I don’t drink wine.)