First, you have to explicitly request a tasting session: we had mentioned it passing to our planner but a few days before leaving for the planning session, we realized none had been scheduled and our planner arranged for one at the last minute. If you're within a week of the planning session AND no one has asked you for your tasting choices, email your planner to make certain a tasting is set up.
Second, go with an empty stomach. We are having a plated dinner with a 90 minute cocktail/hors d'oeuvres hour prior. So we tested out about 8 hors d'oeuvres, 1 salad, 3 entrees (we tried a beef/lobster pairing, a tilapia, and a salmon), and then our dessert (tiramisu). We also opted for the full signature brand bar package but weren't certain on a few of the wine choices: our planner arranged for us to taste those wines and to try some potential substitutions in.
Third, take a camera! Our ceremony and reception are at the GF so the planning session was at the GF convention center kitchen: they set us up with a table and chairs in the kitchen. It was hands down the best part of the planning session.
We aren't having a wedding cake, so I have no info on that one.