We would go to London. I've been there a long time ago and it was great! I would love to take my wife there and stay a couple of weeks and see everything. Beautiful old city. We live in California and have a swimming pool, so we're used to the heat and swimming. London is cool and foggy and would be a great change!
If I'd ever had the opportunity to travel somewhere, I would love to go to Hawaii and California. Amazing beaches, beautiful views, palm trees, delicious food, warm weather, tropical & enjoyable paradise. :)