I want to hire an architect who specializes in designs and drawings
for a four season sunroom and deck in Boston Metro  area.

You may want to check out Light House Designs in Lexington. 

From their website:

No, we don't design lighthouses, although it would be a great project.
The name reflects our emphasis on getting natural light into a house,
and more generally a recognition of how light defines a building.

http://www.light-house-design.com

Some dealers in sunrooms (which can also be known as solariums or
conservatories) local to your area are:

Brady-Built of New England, Worcester, MA:
    http://www.bradyrooms.com 
Glass Structures Limited, Framingham, MA:
    http://www.glassstructures.com
Evergreen Solariums, LLC, Portsmouth, NH:
    http://www.evergreensolariums.com
Better Living Sunrooms/Craftbilt Manufacturing, Northboro, MA:
    http://www.patios.com

These and other links are available at:
The Conservatory Buyer's Guide:
    http://www.almostimpartialguide.co.uk/conservatories/find_a_supplier_usa.htm
and
The National Sunroom Association:
    http://www.nationalsunroom.org/Membership/dealer.htm

You can also search for businesses near your area in the Yahoo! Yellow
Pages ( http://yp.yahoo.com ) by setting the location to your city and
searching for "sunrooms" "solariums" "decks" "conservatories" etc.

This is not an endorsement of, or recommendation for, any of these
businesses.

Whenever you employ a contractor for any kind of construction job, you
should always check with:
  - the local Better Business Bureau
    ( http://www.bbb.org and http://www.bbbonline.org )
  - their local Chamber of Commerce ( http://www.uschamber.org )
  - the Federal Trade Commission ( http://www.ftc.gov )
  - their state's Attorney General's office(
http://www.pueblo.gsa.gov/crh/state.htm )

to see if any complaints have been made against this business. You
should also ask the contractor for the names and phone numbers of
previous clients for whom they have done similar work, and follow-up
by calling those clients and asking detailed questions about:
  - how well the company communicates
  - how quickly they respond to client requests for information
  - the quality of the company's work
  - whether their cost and time estimates were accurate

These and other links are available at:
The Conservatory Buyer's Guide:
    http://www.almostimpartialguide.co.uk/conservatories/find_a_supplier_usa.htm
and
The National Sunroom Association:
    http://www.nationalsunroom.org/Membership/dealer.htm

Bear in mind that companies may have paid for links and that a link is
NOT an indication of quality or reliability. Be sure to do your
homework: at least one of the websites listed on the NSA site appears
to be defunct.

Good Luck!