If i'm going for work, or for more than one day, my MBP always goes with me. Usually have my iPad with me as well, but it will go on short, overnight trips even when the laptop doesn't. iPhone is always with me, because it's my phone.
It's a laptop, not a precious gemstone. When I go on lunch break at work (and I'm usually working in museums or convention centers), it typically just sits out on the table while I'm gone. I'm sure one day, I might fall victim, but to date, I've done it this way for 15 years, and no problems. And, I touch it with dirty hands, too! I've never quite understood the treating of a laptop like a historical artifact.
I'm on holiday at the moment! With my dad, brother and step-mum.
We all have a laptop each, iPhone/iPod touch each and two iPads we share. We took one computer and all the iDevices with us, as we can't let the free Wifi go to waste
Hardly use them though, the iPads are mainly is just used for looking things up/doing the crossword over breakfast! Laptop is used for converting films to DivX (we've got an old DVD player here...) and that's about it. Phones obviously for email/keeping in touch with everyone.
But seriously, if you're by a pool, you don't really need any tech. Unless it's a 15m extension cable and a CD player, to put the good dodgy European electrics to the test There's a nice unguarded socket about 5m away from the pool...
Wherever I go, my MBP and my iPhone come along; if it's international, data roaming is switched off... When in Spain, which I always go to for an extended period of time, I have a phone there that I use daily. iPhone is kept on, though, incase I get messages.
I just got back from vacation a week ago, and I took three pieces of gear:
My blue nano holds mostly music. Since we usually drive to most of our holiday/vacation spots, the blue nano keeps me entertained the whole way.
On longer vacations like this one, I bring my silver nano as well. It's mostly loaded with a couple of movies and lots of sitcom episodes that my wife and I like. If there's nothing on the hotel TV, I whip out my Composite TV adapter and we can watch something funny on the big screen. Otherwise, it doesn't get used much.
MacBook Pro, as a portable Internet station and video library. It's come in handy a couple of times when my daughter's iPod touch has run out of juice and/or she wants to see a movie she hadn't synced. I'm thinking about using an iPad instead, for increased portability, though the decreased storage capacity and incompatibility with Flash would be a considerable negative (you wouldn't believe how many restaurant websites still use Flash).
My wife and daughter took their iPod touches, as they usually do.