Great choices in Channelside....enjoy!
Thai Thani 88%
$$ Channelside - Asian, Thai 615 Channelside Dr
Precinct Pizza 86%
$ Channelside - Burgers, Italian, Pizza 615 Channelside Dr
Columbia Cafe 90%
$$$ Channelside - Cuban, Spanish, Tapas 801 Old
Water St. Ste 1905
$$ Channelside - Cuban, Spanish, Tapas 615 Channelside Dr
Splitsville Lanes 88%
$$ Channelside - Burgers, Pizza, Sushi 615 Channelside Dr
Last time I was in the Tampa area I ate at Anise Global Gastrobar for lunch/brunch but I can see it being great for dinner as well. Great cocktails and food. I had the duck tacos which were amazing and my boyfriend and I shared an assortment of their buns.
Looks like it's only a 3 min drive or 17 min walk from where your staying too.
Along with Andy's suggestions, you might also consider
the Columbia in Ybor City (Spanish/Cuban),
Bernini in Ybor City (Italian)
Bern's Steakhouse (world-class - just a short cab ride)
or Mise en Place- longtime gourmet classic on Kennedy Boulevard, just a few blocks from the Marriott.
No way would I take clients to any of that cut-and-pasted list in Channelside - Channelside is a dining and entertainment complex put there to entertain cruise passengers, not hosting a professional dinner.