The London Eye
I was in London recently and visited the London Eye. My wife and I wanted to go at night, but they didn't have any after-dark times. It closed early.
We originally went on a Saturday, balked at the long line and went back first thing Sunday (10a) and got on straight-away.
The views were good, the whole thing was fun and I thought it was worth it, especially because my wife was really excited about it (partly because she's a huge Amazing Race fan and they were there once). The one regret is that we didn't know about the £3 little map/book that tells you what all the sites are. We found it in the gift shop following our 40 minute excursion. It shows pictures of the London skyline and points out some of the interesting points. It is definitely something the staff should be pushing harder at the ticket counter.
If you have a dozen people in your family, this might be too expensive to do, as it's 40 minutes on a large, enclosed Ferris-Wheel-if-a-Ferris-Wheel-had-large-enclosed-pods. It cost about $25 USD and could get pricey quickly.
For the afraid-of-heights types out there, it's a little dicey on the edges but you can easily sit on the benches in the middle if you start to get shaky. This is definitely no thrill-ride, it's a sightseeing thing.
I detest waiting in lines, preferring using money for convenience over having a huge nice house or car. So, the 60-120 minute wait the first day was a no-go for me. But coming back first thing on the following day solved that issue. It's up to you, but I wouldn't wait two hours to go on the London Eye.
Also, use the toilet before you get in line. 90 minutes waiting + 40 minutes in the pod following a large coffee could leave you in no mood for sightseeing. It could be pretty miserable to spend $25 and then not be able to wait to get off so you could use the restrooms.
