giant valisneria is a nice plant, though for us, it got too big. We measured him up to 3 metres, which is way too big for a tank with a height of 60cm...
Aponogeton-species can get quite big. Personally, I love the Aponogeton Ulvaceus. But they do need lots of attention. They're quite delicate plants.
They grow very wide, though.
If you're looking for something fine, you could try to grow Bacopa. It is a very stubborn plant however, and grows to wherever it wants to.
Echinodorus sp can get big as well. But then again, they grow wide.
One of the plants I am going to use for the background of my aqua-scaping project is Eichhornia Azurea. Though, the tank I'm going to do is only 30 liters,
so that's about as big as I can go
