I own a 2012 Grand Cherokee with the 3.6 Pentastar and use it just the way you intend to use it.
90% city driving from Scarb to Markham roundtrip for work. the other 10% I tow a boat at 1800 lbs dry (1950-2000lbs wet, batteries, gear) during the summer. the 4x4 is a godsend in the winter and on those slippery launches.
Performance on towing the boat is actually quite good!!! I have zero issues with power and passing with it. However, most of the GC's that come with the 3.6 Pentastar don't have the HD braking package. So in all cases of towing, be careful on the braking. Be mindful of your braking distance tolerances. The power has never been an issue. The Pentastar in the Grand Cherokee has been tuned to have a wider torque curve to get the most torque in the broadest rpm ranges. The pentastar shines in the upper RPM ranges thanks to the VVT system. Every instance that the Pentastar is in from the 300, Caravan, Grand Cherokee, Wrangler, to the RAM is tuned differently. If you happen to get a Grand Cherokee with the tow package option I believe you get upgraded brakes (Heavy Duty Brakes) and the auto-levelling shocks in the rear.
I don't regret getting the Pentastar at all, The fuel savings over the 5.7 hemi is nice. I will say that if at least 70% of my driving was highway I would've went with the 5.7 hemi. I hear great reviews of the MDS system (cylinder shutdown at cruising speeds). I'm currently getting 17-18mpg in the city and 19-21mpg on the highway when not towing. When I am towing, my highway mileage drops down to about 16-18mpg. I've already put 94,000+ kms on the jeep with no issues and she drives just like she did on delivery.
Oh yea, a tip I gained from one of the Jeep Forums is to use the slapstick/auto-shift/tiptronic to keep the transmission from going into overdrive when towing. That transmission loves to hunt for the overdrive to get better fuel mileage but it hurts the towing performance.
Hope my real world assessment helps!