A little while ago my smartphone's screen smashed and it took 2-3 weeks for it to be fixed. During that time, I came to the conclusion that I didn't need a smartphone. Eventually my phone was returned and I loved it again and can't imagine leaving the house without it. Simon is probably right - leaving it at home for a month would probably be a good thing - but unless forced, I just can't bring myself to be without it.
Similar situation, although my phone wasn't broken. My wife and I spent about 3 weeks in New Zealand and Fiji for our honeymoon. I toyed with the idea of getting a SIM card, but realized that I wouldn't have time or need to use it.
I found that I didn't miss my phone at all. I had Google Voice at the time, and could text the family from the hotel while winding down. The occasional phone call would have been nice, but I could have used Skype if I really needed to.
Also, my internet browsing habits have changed completely. I only frequent about four websites regularly. Most of my internet free time is spent reading HN Posts and other similar technical articles/blogs that I happen across.
Side note: While I didn't get a SIM, I wish I had purchased some sort of mobile hotspot. Hotel internet access was ridiculously priced, upwards of $20 per day.
