With professional mode you shouldn't need to touch the gamma setting 2.2 is the ideal gamma level and the tv sets it at that as standard, of course i am going by the results with my GT30 but it should be the same with the G30.
Hue settings are quite straight forward if you have a good calibration disc as the differences are apparent immediately, normally any hue adjustment needed is minimal and sometimes not needed atall but it does depend on the picture mode being calibrated.
The best way to calibrate is by using the disc i have but you will need either a pair of blue tinted THX glasses (available on the THX website) or a tv with a blue mode to get the colour more accurate, it's very difficult without either of these! There are colour filters included with the dve basics calibration disc but i didn't find the actual disc very good, do a google search for 'free hdtv calibration tool' and look for links to AVS which is the disc i use. I won't say anymore for fear of breaking house rules (have i said too much mods? if so apologies) but you should be able to find it, use that and see if you get better results but don't forget you will need a blue filter or THX glasses to calibrate colour.
I've had no issues with brightness or contrast and my tv is pretty accurately calibrated now (of course a professional would get it even better) but it's strange that you are having issues, simply ramping up the brightness is not what you should be doing as that will affect picture quality and getting the right balance of brightness and contrast is what you should be aiming to do.
I have no knowledge of the S30 i'm afraid but the G30 has been well reviewed from what i have seen so perhaps after giving calibration another shot it still doesn't seem right you might have an issue with the tv as this is not mentioned in any review i have seen.
Have you tried normal mode on the tv? I use this for tv viewing both sd and hd and then use cinema, THX or professional 1 for bluray movies and game for games and it's lovely on all sources...THX gets used only rarely with THX certified movies and i have cinema and professional 1 calibrated with different colour settings so i tend to choose which is better for the movie i'm watching.
That reminds me...the colour temp can have a vast effect on brightness and contrast! If you use professional or THX you will find the colour temp is taken out of the options but if you use normal, cinema, game , dynamic or photo you get the option of colour temp. Try it set to cool or normal, cool introduces much brighter cleaner whites but it can look a little blue on some sources but may solve your issue.
Hope that's of some help to you, let me know how you get on with it.