Get the bike working absolutely 100% tip top, then take as many spares as you can fit in your bike bag/weight limit. Bearings shouldn’t really be an issue, they don’t suddenly go wrong in a week… The question isn’t so much “Will I need that”- that covers the basics, but then it’s “what else can I take that might be useful”
People say “take spokes if they’re a weird size”, I just say take spokes. Even if you use the most boring spokes in the world, tracking them down still takes time. It’s all about not wasting your holiday in bike shops.
Remember tools too if you have anything odd on the bike- special spoke keys, that sort of bollocks.
All the mech hangers and pads in the world. A ton of tubes too if you use tubes (that way you can lend one to Stevo 😉 ) I went through an extra set of pads last year as it turned out one of the sets I took sucked, glad I had extra spares. I bent a hanger badly in a crash and another one apparently was weakened and just snapped on a blue, so was glad I took 3 😉
If you’ve got a compatible rear mech on another bike, it’s worth nabbing it. I
took a whole spare brake system- was going to just take a lever but that worked out simpler. It was a rear, if I’d had to bodge it onto teh front I’d have probably just cabletied the excess hose up.