Guernsey is a fantastic destination, less than an hour's flight from London, for weekend escapes and longer battery recharging. There is a wonderful range of outdoor activities for people who don't get enough fresh air, and still the occasional tax-free bargain to be had from one of the many artisans still producing hand made goods here in Guernsey.
Don't forget that Guernsey is only 24 square miles, so everywhere is close to town, countryside and beach. You may wish to hire bikes, or a car for your stay. There are many cycle paths dotted around the island, but it's just as easy to use the bus and the occasional taxi to get around. You'll probably find you'll want to walk to most places when the weather is fine.