My parents went to London about 6 years ago and loved it. They went to Harrods (sp) and just picked a few little things, it was not too expensive. They went for a supper cruise as well, but that was pricey...$450.00 for the 2 of them. They were lucky though, they have friends that live there, so they were able to go to places that most people don't see.
My father attended Scotland Yard back in 98, got me some mini statues of famous buildings and a Bobby Hat. Pictures are always a nice touch. Just apply the same concept to whenever you go site seeing yourself.
my brother went there after his sophomore year of college with a bunch of friends. He brougth me back some postcards, a "stress" ball with some London phrases on it, and some coins from London. Pretty cool stuff seeming I haven't even left my home state. lol.
You need to explore your surroundings. There is so much to see and do out there. I've been fortunate to travel a bunch. I've never left the country but I don't think I would care to unless I went to Australia (that is the one place I've always wanted to go)