I am interested in worldwide travel insurance to cover multi activity, baby and US travel. But I want to get the most for my money, not just the cheapest

I would call an insurance broker - they have a range of policies that are half decent. Internet policies (aggregator especially) tend to exlcude pre-existing medical conditions, terrorism cover and have high excesses (to get the price down) whereas a broker will offer you a better policy.

One of the best cover wise is the BIBA travel insurance scheme - £40 excess per person per incident (not per section) with a £80 excess maximum per family. The annual policy is 45 days a trip.

With regards to activities, quite a range is covered but a broker will ask you about higher risk activities and recommend a policy that covers them.