Most restaurants can accommodate. The only places we were not seated together are Sci Fi, Coral Reef and Crystal Palace. Although they won't guarantee seating at one table, they try very hard.
We had a group of 13 last year and didn't have trouble getting seating. We ate at The Wave, Ohana, Wolfgang Puck, and Big River Brewing. We weren't split up anywhere.
I took a trip in April this year and we either had 11 people or 15 people in our party at various meals. We were seated together at one table at the following:
Mama Melrose
Chefs de France
Boma
Via Napoli
At Tusker House they sat us at two tables next to each other, which was actually great because the characters hung out for photos in the area between our two tables.
We usually have 11 and have always been seated together or at least at tables right next to each other. The only one that I remember that we were not able to be together was Sci-Fi.