A little update to end the year, and hope to gain some answers in to how I can make my tank half decent for 2012

..
It's been around 18 months now since the big tank went tropical, and over those months I have probably spent a sum of money I dare think about on live plants and plant food, so you'll share my dismay when you see what it currently looks like:
The tank is now a mix of live plants to the foreground, and synthetic to the rear as I was sick of dying plants floating around the place. It would seem some plants are doing okay (and always have) and some just never manage to look alive. I've always gone for the less demanding, 'robust' plants but it would seem even these can't abide living in my tank.
My anubias (as shown above) are the only plants that I'd say looking healthy, and I'm pleased with the way they're growing into the redmoor wood..
Compare to the Amazon swords and such.. Leaves constantly dying off and new shoots are pale to the point of being see through from the start. I just cannot sustain a healthy sword or similiar plant (even the valias die off).
There was a time when I had all the crypts at the foreground, I really want to try and get this look again as it was dense and layered and created some beautiful colours to highlight the fish when swimming by, and crypts do seem to survive my tank a little better.
I'm just unsure as to where I am going wrong. I dose liquid ferts as per the instructions and it never seem to sustain the plants, I'm not sure if I should increase the lighting or what - either way I'm finding my tank a bit of an embarrassment for when people visit and I've this massive aquarium with half dead plants inside

and clearly I need to find the cause of my issues before I waste yet further money on filling it with plants.