Help selecting a bunch of items at once

[mkennedy]

I draw room additions, so I always have new and existing - when I draw a framing plan I like to put the new and existin framing on seperate layer, which involves lots of selcting. My shif tselect tool seems to max out after 5 or 10 items, dropping the entire selection set in favor of the most recent addition.
Group selecting picks up walls and stuff that I don't want to select.
Any thoughts on a great way to achieve this desired end result?