What vendors get a plate?

The DJ and Photographer. Make sure you feed them!

My caterer recommended only feeding vendors whose contracts require it. So far for us that's my planner and her assistant, photographer and second shooter, and 5 band members.

Ask the vendors if they want one! Our photographers were there for 5 hours and they specifically told us not to have a meal for them because they preferred to bring their own food, as they bring sandwiches that they can eat quickly and then go back to photo-taking... they said they usually don't have time to eat the venue's meals anyway and to save our money and not bother paying for their meals! So we ended up just tipping them extra with the money that we would've spent on their meals lol.

Most vendors are not like that though, most WILL want to be fed... but it is worth asking! Just say something like "we are of course happy to provide you with a meal but I just wanted to see if you would want it."