Home Improvement Architecture Phase
It wasn't hard for us to decide to use an architect:
1) We wanted to "not-screw up the house"
2) We wanted more ideas, but most of all we wanted the technical expertise with regards to code, regulations, etc.
3) Usually architects can be creative with respect to space usage, how room shape/size impacts it's use, etc.
So we got a referral for "Creative Classics, Inc." - a [apparently] one-woman architecture company in Falls Church, Va. She was nice, came when she said she would, etc.

We hashed out some ideas - here's a brief list of our ideas concerns:
1) Make deck into MBR, Make Den a MBA, push out the back wall of the exisitng FR;
2) Don't hurt roots of huge maple tree along side of current FR;
3) Use as much of the existing structure as possible;
(I think that's about it...)
Final View
ADVICE:
Let the architect know what you expect. If you have no clue what you want, say so. If you know what you want, but you're open to suggestions, say so. If you know exactly what you want, but simply can't produce the drawings, then say so.