I flew the C172 with and without the retractable gear during my training and found it to be a comfortable plane to learn to fly in. The RG version hangs a little better in the air and is a very nice IFR platform for the IR training.
On the basis that this aircraft is supposed to do just this, otherwise, the 182 would be the better choice for travel, perhaps anything that makes it cheaper to operate would be good. Wherever you can, reduce drag, find a more efficient engine etc.
/LnS