I have just gotten back from the Isles of Scilly and just want to say that it is probably one of the nicest places I have visited in the UK. It's not that cheap to get to, and its a bit expensive for food etc on the island BUT the weather is amazing (think tropical island), the beaches wonderful and perfect for little ones to swim, look for shells and for the grown ups to sunbake. You can hire bikes and prams to travel over the islands. Lots of wildlife to look for and things to see (museums, gardens, ruined buildings etc). The people are really friendly, no crime, and pet friendly as well. One of the restaurants is michelin starred!
I just wanted to rave about my fabulous 4 days there. Great place to go for a short break.