Two things come to mind:

1. last week at JC Penney's they had 3 styles of roll-aboard sized bags in bright colors on display - my 5 yr old tried to talk me into buying him the electric blue one - and they were very easy for a kid to handle, both getting the handle out and wheeling it around. Granted 5 yr olds are bigger than 2 yr olds, but might work for you.

2. if you want a good quality bag for the long term, we've been very pleased with the luggage from both LL Bean and Land's End, and they have roll-aboard sized bags.
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You specified suitcase, so I didn't even think of this at first. My son has a small rolling backpack that he's used as his carry-on since he was 2. Simple pull-up handle, zips open across the top, holds his books and toys. Sorry I don't remember where I bought it, but I remember thinking that the cheap backpack were much better made than the cheap suitcases.

Brainflash! I bought the backpack at a chain drug store during back-to-school season - about now, scarily enough.