Kade, what I can really suggest to you is try looking up floor plans of buildings to make them less boxy. But for a start, you could try creating rectangular, L, T, or H shaped buildings, or some combination of those.
As for the exterior, consistency is the key. Make sure whatever you add on the façade will match with the general style and feel of the building. One of the mistakes I used to make with my older town-houses was that they ended up looking like some weird wedding cake due to over-ornamentation.
I hope this helped, if you need more help post pictures of your w.i.p. stuff.