It depends what you're looking for in London and where you are staying. There are some great places in central London, especially in Soho which is such a nice little area as well! I've heard great things about the Rum Kitchen in Soho. If you're in London, don't waste your time with Pizza Hut/Subway/McD troute, actually go out and look for great local businesses who make the most of fresh produce for good prices.
Like Pheesh I also HIGHLY recommend Barbecoa, it is very pricy though but so worth it - great menu, atmosphere, service, and fantastic unforgettable food! It's also right next to St Paul's Cathedral so you get to have a lovely view too.
I met up with Goldenboko and his entourage yesterday. You'll be pleased to know I did indeed take the lad to Soho. This is a tip for anyone who goes to London who likes steak, there's a cool little indie pop up called Flat Iron: http://flatironsteak.co.uk/ where you get a steak for £10 (!!!!) which for London is insane. And if you click the link, look at how they serve it. Yes, you get that knife too! Boko and his posse really enjoyed it.
I'll take one or two of you for EoFF Con. Start sucking up to me now if you wish to be a Chosen One.
Rome was probably my least favorite city to visit. It was basically NYC with ruins in the middle. And it was ungodly hot.
Well I didn't have much choice on the time of year since I was still in school at the time :P it also was the hottest 3 days in 30 years when I was there. The Vatican was cool. But Rome just felt too modern compared to Venice and Florence which I thought were amazing cities.