Ah, a perennial WIS question. I used to agonise over this. What to travel in? Diver/beater for the pool? Something smart for the evenings? I have, in the past, taken up to about 4 watches with me and rarely worn some of them. Rethink!
Extra watches are a risk. In some resort towns your Rolex/Omega or whatever will be spotted. (@Roxyben - you might be OK on Mull!) Do you trust the hotel safe? How do you carry them? Not in checked baggage for sure. Carry on bag, then. Yes, but they take up space, are separated from you in security (briefly) and may come into contact with phone/iPad in a bag...etc....etc.
Solution. One watch. On the wrist at all times.
I went on five holidays with the CW Trident GMT. Great all-rounder, performed brilliantly, but in the end I had to admit it was just a bit too big and heavy, so I sold it.
I haven't travelled since Christmas and New Year 2019/20 in Cyprus, but next time I go away (hopefully Greece in Sept/Oct) I will take the MeisterSinger Metris. Cool, blue, 200m WR, strap-adaptable. Perfect for a chillax holiday. After all, I only need a vague idea of the time. Breakfast time, beer time, lunch time, siesta time, gin time, dinner time, stagger home time...
I'm hoping to go to Cyprus for my usual Xmas/NY jaunt, having missed it last time. In which case it will be very likely to be the UN. Proper travelling watch.