Most USA trains rolling stock comes with metal wheels, if you prefer aristo cars you will need to replace plastic wheels with metal ones for best operation. ive used aristo wheels on alot of there cars but they do get quite exspensive to do. i recently was told by Robbie at RLD hobbies about accucraft AML 1/29th wheels he had just gotten in, so i bought a couple of cases of them and they are great looking wheels and fit my new 2 bay aristo hoppers great and were 7.00 a set cheaper than aristos. they worked out to be 11.00 a set of 4 whitch was a great deal. As far as couplers go i prefer g scale kadees, in my opionion they are the best and have work out to be cheaper than aristos. i sell all my extra aristo couplers on ebay to recupe the cost of the kadees. i recently sold 5 pr for 31.00 on ebay and that paid for 5 pr of kadees, a no brainer if you ask me. i prefer body mounting couplers as i like to run long trains, and i also like backing long trains as well and with kadees theres never a derailment ....