I thought I'd get the party started by talking about London!
Here's my to-do's if you ever make it there. Remember, these are just MY to-do's, yours might be different. In fact I think it'd be great for people that have been there to talk about their experiences.
The first thing I want to bring up is, when you travel to places you've never been to, it's ok to do touristy things. I mean, you're a tourist right? Nothing wrong with taking guided tours, or going to tourist hot spots. That's part of the travel experience.
London Eye. Yea, it's a ferris wheel, and yes it's touristy, but it gives you great views of the city and if you can make it on near dusk, and it's clear, the views are beautiful. It's a 30 minutes ride, but tack on some time before to wait in line.
Tower of London. I absolutely LOVE going here. I have gone every time I've been and am never disappointed. The history. The building architecture inside and out. Just so cool. Have lunch at the restaurant, the food is really good! (particularly the spaghetti, and be sure to get a fairy cake!)
Harrods. Even if you don't like shopping, it's still really cool to walk around this place. It has absolutely everything, from electronics to lingerie to electronic lingerie to a grocery store to restaurants. An absolute MUST is to stop by the Chocolate Bar. Nothing but chocolate products. My fave - a brownie and what I call and iced chocolate. They call it a shake but really it's more like they took a hot chocolate and whipped it up and poured it over ice. HEA-VEN!
Hyde Park. Take a leisurely stroll through Hyde Park after you leave the Chocolate Bar at Harrods. It's a great little breather. The Peter Pan statue is there, as well as Princess Dianas memorial.
Kensington Palace. It's where Diana lived. Such a beautiful place, again with a lot of history.
The Imperial War Museum. I didn't think I'd enjoy this place at all, but it was one of the highlights for me. I could have spent WAY more time in there. My sister, who isn't into this sort of stuff at ALL, told me to go. It didn't disappoint.