I can see very few needs that can be solved by the iPad best.
Assuming you are going for all Apple products:
You want to listen to music. Get an ipod
music + games + emails/browsing on wifi. Get an ipod touch
phone + all the above: Get an iphone
Actual work: get a laptop + some phone that tethers when no wifi is available
So the ipad would be great if somehow you want something to browse lightly on or email without typing too much and you don't need/own a laptop. Otherwise any laptop is light enough to bring anywhere you would bring an iPad.
One place I see the iPad shining is as a car device. cheap, big screen, tons of apps and 3g. You could get as many apps as you can possibly use in a month and still be cheaper than car's integrated nav units. Add a little device and you have the backup camera too.
Maybe also as some kind of work terminal when a phone is too small and a netbook too big. Not that there is much of a difference and the keyboard is a big +