I am also going to have a go at this! 
Samoh, yours are going to be fabulous I know. Ok, here's a few ideas.
First, I'd move the gnub game to the rear and move the garden to the left of the house closer to the kitchen and of course, move it more to the rear.
Most folks with big, fancy houses don't want a veggie garden or game to be seen from the front of the house.
Your Sims loved my little Zen garden. Jumped up and down, clapped hands and yelled whoo hoo at it. Lol Here's a few of the ideas I played with. I saved none of them but there are so many ways to go.
This is the little Zen spot. I felt it kind of welcomed you in and it would be a quiet spot when looking out the window. A bigger contemplation garden, either Oriental in tone or more European could be done in the back. Maybe raise the ground a bit, add fountains, sculptures, a pond.
This is where I changed the path to the house. Wasn't sure if I liked that big center thing but the path was so long before you got to the sidewalk I felt I had to do something to break up that long line.
Added two large bamboo trees that arch together overhead. I rather like that but not sure it doesn't overwhelm the low roof line.
Ok, I liked the FabuFoo but they are very expensive and not sure you have them.
Here is with formal flower edging along entry with formal shrub fence. Ignore the weird grass. You simply can't match EA's grass exactly and I was trying different grasses.
So, that's bits and pieces of some ideas. I really did not realize how challenging it would be doing someone elses landscaping for two reasons. One, I do not know the budget and I can go waaaaaay wild with landscaping and spend a fortune. Second, my tastes and yours could be extremely different so I'm kind of second guessing. Oh, and there is a third, wasn't sure if I could move the veggie garden and game which actually would make a big difference in what I would do, and wasn't sure if you intended to fence it in at all.
This was fun. I think I'm going to just go ahead and fool around with it to completion, no matter what the cost, and then save it. Of course, I am NOT touching the house at all as this is your baby and it wouldn't be right. I sure wish the game wouldn't put the houses you place so far back. That is an enormous front lawn.
Edit: Ok, looking at the low roof line and sprawling, ranch style nature of the house, I think the more formal look is really out of place. I'm thinking some rock piles, (which I am VERY clumsy with), would be better and maybe not that huge center section at all. Maybe have the path meander to the house rather than the straight line. If it was a two story house, the other path and formal stuff could work but it would be a ginormous house then.
