Although I have seen an equal success in away and home uses of Great People who join cities, sometimes I really wonder what is best for their full benefit.4
Given that no techs will get more than a 50% bonus from being researched by a GP or any WWs exist that engineers can finish, is it better to have GP settled into fledgling cities so that they can grow faster or should they be kept in larger ones to add to the higher rate of research/gold/productivity?
Sorry, I don't understand what the red is on about, what 50% bonus?

. Settled great people by the way won't increase the growth of a small city apart from through the food or hammer yield of a super specialist (+1

for GScientist, +1

for GMerchant or +3

for GEng).
In case this is whats being said, great people can instaresearch techs in their entirity, and GEngineers can built wonders outright, what they do is provide a lump sum thats modified by population and doesn't overflow.
As a result bulbing techs tends to be relatively poor in the very early game as techs are so cheap, and golden ages or corps tend to be much stronger i nthe late game, but in the mid game they are very strong indeed. There are of course exceptions, bulbing maths with a GS, while wasteful in terms of

, can be very strong in allowing Oracling of Construction, or just from chop

.
Effective bulbing does require foresight and planning, you will definately want to consult the GP tech priority lists in the war academy.
On settling, the only great person that directly increases growth of a city is a merchant, and thats just +1

. Others help indirectly through

but only a GEng is worth mentioning there (and would still be a massive waste). If your going to settle them your going to want to concentrate them in core cities with large multipliers, the most effective strategies involving settled great people usually involve settling masses of them in the capital, with a focus on great prophets as their

gain the bureacracy bonus.