Gocity London pass-is it a good deal?

If you just want to see those three sites, it doesn't make any sense - it is a lot cheaper to book directly.

If you think about it this way, realistically you can manage a maximum of two sites a day. But you'll want to do other things like go shopping, walk the streets, visit the parks, and visit museums (many of which are free). So in your five nights, discount your arrival day, allow two days for museums like the V&A, British Museum, National Gallery, Imperial War Museum etc, and one day for shopping. Suddenly you're really only going to have one day, enough time for two sites. Perhaps you don't like museums, so allow another day, which still means no more than four of these sites.

Others may have different opinions, but I can't see it being worth it.

The answer to this question is always, "it depends." It depends on your anticipated usage and itinerary. First make a list of where you want to go and when. Then price out admissions for those places that are also covered on the London Pass and compare to the cost of the pass. Now you will know if it is a good deal for you or not. No other way to do it that just isn't some person's personal opinion or bias.

Advantages of the pass include easy entrance at many locations, flexibility to change schedule a bit more than with prepaid set admissions, and the ability to try new things simply because they don't cost anything additional. For example, I did the London Eye for the first time in many visits simply because it was included. I would never pay to ride it otherwise. I enjoyed doing it once.

Disadvantages of the pass include that it doesn't always save you money (must price compare in advance) and some people are tempted to overbook themselves trying to squeeze every last penny out of the pass.

The more days included in the pass, the more likely it is to be a better value as the cost per day decreases dramatically.

A key factor in London is the existence of so many free/donation-requested, world-class museums. No pass will help you with those. It's not just a matter of what the pass covers that might be interesting to you. You need to look at the big picture, the universe of all the possibilities in London, and decide on your top priorities. How many of those are covered by the pass? How many will you really have time to see? Compare their entry fees to the cost of a pass.

There will probably be major admission-fee discounts for your children. Be sure to take those into account when you calculate the cost of buying tickets directly.