When you have the floor plan, I would definitely keep the real wall thickness (even together with the inner walls) and pull the walls up instead of only the outer faces.
It is much quicker (you need not draw all the vertical lines separately) It is way more realistic even from outside views. Single face walls always give themselves away.You say you may want to add the interiors later. That would mean a lot of additional work when you could do it much simpler in one action.
Some additional suggestions: always separate your geometry by grouping it. Say you draw the outline of a house and pull it up to a bit of height to give it some foundation (and thickness for your floor). Make this a group. Copy its top face outside the group and now offset and draw your walls on this face; pull them up and then immediately group all your walls. Go on modelling in the same fahion. This will allow for much better control of the whole model both while modelling and later when presenting.
Use components for anything that is more than once in your model (say the same window three times). Groups and components are very similar in nature but components have some additional advantages (maybe later in detail)
Do not forget that layering - as opposed to CAD - will NOT separate your geometry. It is merely to control visibility in SketchUp. Also, do not EVER put ungrouped geometry onto any other layer than Layer 0. In fact, do not even change the active layer and always draw on Layer 0. Otherwise you mess up your model like this:
[flash=640,500:34r2tjg3]http://www.youtube.com/v/fBdP499iw0Y[/flash:34r2tjg3]