To add:
I think the key to brewing these low gravity beers is to use the most flavorful ingredients you can. If a normal strength grain bill calls for, say
8# 2 Row
1# C40
.5# C120
.5# American Biscuit
Fermented with WLP001 California Ale
I would start lowering the base malt until I got within .005 of my target gravity, keeping the character grains more or less static. In addition to that, I will replace domestic grains with their more characterful European counterparts. Taking the grain bill above down to a 1.030 beer, for example, might look something like
4# Maris Otter
.75# Medium English Crystal
.5# Special B
.5# Belgian Biscuit
Fermented with WLP002 English Ale
With those changes, I would then raise mash temp, if you are looking for a full bodied finish, or go with the less attenuative yeast. Hopping, of course, is highly dependent on personal preference.