Hi Lunies,
This time 'round, while in London, I'm fortunate enough to be staying with a fellow lunie who already booked the hotel. It's a very nice classy expensive hotel, but because he was able to get a decent rate on it, we're going for it. (Might as well spoil myself a bit, yeah?). :-] :-]
However, had I been on my own, I would have returned to a place that I have enjoyed in the past. The place had gotten really great reviews several years ago in travel magazines. My brother and sister-in-law and family were the first to "try it out" and subsequently, they recommended it to me when a few of us lunies traveled to London a few years ago to see PG's Still Growing UP Tour. The name of the Hotel is The Windermere Hotel, located in Victoria, London. As Caste mentioned, this hotel is also within walking distance to Victoria Station, which is useful when traveling to/from anywhere else in London. It's also a very nice area and close to lots of historical sites.
I'm not sure what the prices are currently and whether or not it's within your budget, but when I was there, it was reasonable, the staff were very friendly, the food was good and the rooms were nice and clean.
I'm not sure how close it is to the venue, but as I've mentioned, it's close to all forms of transportation.
Here's the link:
http://www.windermere-hotel.co.uk/
Good luck with your ventures!