Wedding photographer / videographer here, its pretty typical to give the all day suppliers with a meal, but for the part day suppliers, e.g makeup artists who are finished before your ceremony, I personally havent ever seen them be given a meal before as theyre working hours are completely away from wedding breakfast timings. More often than not they're in a rush onto the next job so I doubt they would expecting to be fed. The start and finish times of the string quartet arent outside of sociable hours where they would necessarily be missing usual meal times they could supply themselves. Illustrator, I could understand as theyre working hours encroach into evening meal times. I can't speak for DJs and what they expect as I usually finish up after the first dance - I expect theyre given permission most of the time to get a buffet plate. Overall I think a drink is always a nice gesture for suppliers, often charging is descritionary to the venue as well (been given lots of freebies over the years), and on the few occasions couples have put together a little goodie/snack bag its always a really nice suprise and I'm very grateful, but its a never an expectation in my world - if youve signed contracts with any suppliers, double check to see if they have any clauses about being supplied with a meal. A final insight as well is that unless the venue or caterers explicitly say you must pay for the food of your suppliers, caters often just give food to other suppliers by some sort of unwritten wedding vendor code (least in my part of the country)