I originally started this thread and am glad to see it again.
We still have the Vue and it's proven itself to be a darn good vehicle. It may have a little road noise and some clearly cheap plastic bits but it's been utterly reliable and routinely delivers 25 mpg (give or take) to my wife (80/20 in-town). On top of that it's hugely flexible with it's 5-door layout and comfortable for my family of 5.
As far as tips: unfortunately I don't have many.
The car does seem to be heavily affected by cold temps (losing 2-3mpg in winter time) so I have to believe a well designed warm-air intake could be beneficial in colder weather.
Warm-up times also seem a little long-ish (not terrible, but too long for my liking) but you've already done a grill block.
Other that that keep your shift points low (neither of us typically exceed 2000rpm between shifts), tires inflated and coast for all it's worth (my wife is a master at this). That's all it's taken for us to get mid to high 20's from it on a consistent basis.