I think you are definitely "in the ball park". Your W is pretty large so less than an ohm is for sure possible (depending on your cmos process). Probably the best way to see the resistance though is using the simulator (i.e. measure current Ids and voltage Vds). Also, you need to think about the type of application that the nmos is used in. 1 ohm or less might be required when the transistor is on (i.e. saturation)? Or do you use the transistor as a linear resistor (i.e. linear region)? Anyways, your resistance is reasonable.
.analogLow