I normally do 17k miles a year and its all commuting, I use a good oil and change oil every 12k miles, Due to the low revs when bumbling around a motorway oil degradation is minimal.
A good modern oil should last a lot longer than 5k.
Obviously this is totally down to the owner and can depend on your annual mileage, at 5k service intervals I would need 4 services a year.
To the question, yes the ct is pretty much designed for commuting, its comfortable and smooth on a motorway and with careful driving you should get 55-58mpg (that's what I get)
Cheers Darko