Regarding your differences in lenses post ... I can try and help. Do you have different lenses that you are looking at?
Here's what I have in my bag:
Nikon 50mm f/1.8 - my prime lens
Super sharp, opens up wide (great in low light), zoom with your feet
Fantastic for portraits
Nikon 28-80mm - my kit
Not great in low light: variable aperture, short zoom
Good walking around lens
Nikon 70-300mm - my telephoto
This is the lens I have on my camera the majority of the time
Good compression, good variety in focal lengths
Tamron-F 2X - my doubler
Doubles the focal lengths of any lens I connect to it (full 2 times doubler, as there are other options such as 1.4's)
Great in combination with my telephoto as I then have essentially a 600mm focal length.
I lose about 1 - 2 stops of light, but I only use it outdoors so it's not that big of deal
Macro
I have a filter that gives me a faux macro, but I really am drooling over Nikon's 105.
The 105 also has great compression which is fantastic for portraits. It also gives a true macro at a ratio of 1:1 where others don't quite give you the 1:1 magnification of objects.