Welcome to GenVibe! What tires does the car have now?
Upgrading the width of the tire also increases the height (which helps the ride), but as you stated, rubbing can become an issue. On the Vibe I wouldn't go with anything larger than 10mm wider, unless you are willing to change other suspension bits.
It's easier to find a tire that is more comfy, than it is to change the tire size. Look on tirerack, and search for tires that are All season passenger \ Grand Touring.
Here is a quick comparison for Grant Touring tires.
https://www.tirerack.com/tires/surveyre ... alve+Stems
Edit: I have the Pirelli Cinturato P7 All Season Plus (16") tires on my Vibe now, and they are more comfortable than the High performance All seasons I had on previously.