This Architecture set from Lego is easy to build, very portable, and a nice piece for any architects on your gift list.
At 240 pieces, this is a small set---about 4x4 inches on the base when assembled. This makes it quite portable for "show-and-tell" at a child's school, or for taking to the office for display on your desk. It's a pretty sturdy build, so no worries about small pieces breaking off in transit or in play. It's an easy set to assemble, should take less than 30 minutes even for a novice builder.
NOTE: there are not any "specialty" pieces in this set (aside from the printed flats that say Rockefeller Center). So those of you with extensive collections could build this easily from your existing Lego pieces. The instructions can be downloaded from Lego.com for free.