Location, Location, Location!

Whenever I've heard talk about O'Neil style space colonies. L5 is
always the suggested
location, but what other orbits/locations would be good? Would there
be a limit to the
number of colonies that we could safely place at L5?
What about the Earth-Sun Lagrange points, like the SE L4 & L5 points?
Are these also referred to as Trojan orbits? What about other Planet-
Sun Trojan/Trojan orbits/points? I know that there are considerable
numbers of asteroids in Jupiter's Trojan orbits that would make handy
resources for the colonies.
Other locations that I've heard of are:
L1 in relation to the exploration of the Moon, it would allow access
to any point on the
Lunar Nearside, also would allow for assembly and launching of deep
space missions, disadvantage it would require more station keeping
than at L4 or L5.
Also in relation to Mars exploration, there has been a suggestion of
using the Martian Moons as bases/staging areas. I'm interested in
writing a story set in solar system and where humanity has expanded
out and just wanted some ideas of where we may go to colonize/settle
Any comments/suggestions