I am looking to restart my small landscape architecture business. I used AUTOCAD with a LANDCAD add on over a decade ago. An unsure what version of AUTOCAD to buy as the 3D version looks like it has a lot more than I will need. I do want to produce good looking perspectives, sections etc - so graphics are important.
If you still need an add-on, or the same add-on, I suspect you still need full AutoCAD, 3D or not: most add-ons require full AutoCAD's open prgramming languages to function.
If you don't need any 3rd party add-on, download and use the LT trail for 30 days and decide for yourself if it's "good enough".
If you buy the full AutoCAD 2012 version, there is a compatible program (Plant List Professional) that drastically reduces the time it takes to add all of the plant quantities and costs for a drawing. It costs a bit up front but is easy to learn and the time it saves our office in number crunching makes it worth it, especially when we have to make changes. There is a free trial if you want to check it out.