Driveway & Garage & Landscaping, Oh My!

After meeting with a few architects, we finally found one that came highly recommended and fit our budget! This is our biggest and most exciting remodel project. We originally planned to just pour a driveway this year and do the garage next year, but overall cost for building materials, labor and contractors is so low right now we're going to try and complete it all this summer/fall.

Our general plan is to:
1. Build a 2-car garage with a roof deck on top
2. Have access from inside the garage to our basement
3. Have access from the roof deck to the main level of the house (either through the current laundry room or the current pantry)
4. Have access from the rooftop deck down to a garden area on the South side of the property
5. Adjust grade of the driveway
6. Adjust grade/level of the garden area and possible add retaining walls

Our architect stopped by to take measurements last night, and we have more ideas than we know what to do with. The biggest decision we have to make right now is whether to do an attached or detached garage. Each comes with it's own challenges:
Detached - We lose more square footage of the lot to space between structures and we may have to move one side of our current retaining wall in order for a car to access one of the garage bays. The door to the main level from the roof deck will be at a different location than the door to the garage below which could look odd.
Attached - Would be a more complicated build to attach to the house and may require additional engineering tests and drawings. We would have to dig down (at least a few feet) to inspect our current foundation to see if it could support another structure. There are a few possible ways to keep most of the weight from the garage from falling on the house, but all may be more expensive to build than a detached structure.

Decisions, Decisions.

Here is how the backyard looks now: