Have a looking around your area at developments of the same size that you like and find out who drew the plans?? Sounds simply!!!!
Talk to local builders, after all they know the game and have worked of the plans drawn by most architects in the area probably
Also just have a chat to the architect on how they would lay out the site without getting specific plans drawn
7 acres is a fair size plot talk to auctioneers also on what is in demand in the area and what kind of prices are out there. Might be worth looking at going a bit more high density, if planners allow it, or a lesser amount but high spec houses. Depend on your location.
Best of luck.