Should I plan on booking tickets in advance for the London Eye, Tower of London and Kensington Palace? Are there long lines for these attractions if you don't have a pre-purchased ticket? I don't mind waiting in line, but I don't want to waste my time in London standing in lines!
I've heard to wait until the day-of to purchase tickets for the London Eye, depending on the weather that day.
If you can get Tower tickets online and at a discount then yes. In summer months its always crowded and even with advance tickets I'd be there before it opened to get in line. The advice about the London Eye is good, wait till you are there to see if the weather is going to allow a great POV. can't comment about Kensington Palace, have only walked by.