I have been on this and for me it was a waste of money!! The weather was appalling at the time and we were swaying from side to side. I am only glad I did not pay full fare, paid oap rates. If you go make sure the weather is good and you have good visability.
We did it in September and enjoyed it. A good day weatherwise is desirable. It's not a particularly long journey and you can just do the round trip and not get off. The views are excellent with good weather. I wouldn't recommend the Aviation/Discovery Experience - in my opinion it wasn't worth the extra cost.
I was going to mention the Thames Clipper - isn't it crazy!
The first time I got on it (at the millennium pier) it chugged off quite slowly until it got to Tower Bridge and then all hell broke loose - I've never been on any water craft that accelerates like that thing!
only if you've got good weather, which it sounds as if you had. Morning with the sun on Canary Wharf is good. They used to have exactly four season ticket holders (a friend of mine was one of them, she used to work at the Crystal). Now they have none. So I wouldn't bet on this lasting forever. Go see it while you can.
The Docklands museum is back at Canary Wharf. If you're there, have a look at the roof garden over the Crossrail station - free, just walk in.