Okay, let me help:
When It comes to buildings, I would recommend the creator houses, or brick buckets for little kids. They may be young builders, but they are wondeful parts packs. The Agents mobile command center is great as well for it. Also, you will find that the Bionicle Playsets from 2005/2006 are amazing parts packs.
And make sure you pick up at least two of these:
Now everyone needs an SUV, so I would recommend this:
http://www.brickshelf.com/gallery/kin/By-K...e/2009/7635.jpg
The trailer can be used as parts for buildings.
Here is a great set:
And for figures, this set that is on Lego shop at home is wondeful:
And lots of things form here.
Hope that helps!
And not sure if you are getting it or not, but the Lego Harbor as well.