I'd have more water than land. Mine spend way more time in the water than out of it. For the parts I want as dry land, I just pile medium to large size gravel up till I get above the desired water level, then add whatever material is desired for the land portion. Plants are self watering when you do it this way as their roots get down to the water in the gravel layer. I feel that the plants help keep the water clean and also the gravel should be a good place for nitrosomonas and nitrobacter to colonize and also help maintain your water quality.

The drawbacks can be that your land areas are higher and leaves slightly less vertical space for plants. And the larger your viv, the amount of gravel needed can get quickly make your viv too heavy. However for my w20" x d10" x h12" (w50cm x d25cm x h30cm) tank, neither of these has been an issue. I have my land adjusted so it takes one full gallon (3.8Litres) of water. As I use no pumps or filters I change it every 7 to 10 days.