D.W.
I'd highly recommend finding a store that carries several varieties (we only had a Babies R Us locally) and try them out with your 2 year old in the store. See how they are to maneuver through aisles, around racks, etc.
Try to anticipate where you'll be using them most often. We took ours (Graco DuoGlide) on a trip to San Diego when our younger was 12 weeks old). Manuevering around an airport, hotel, museums, etc. in a front-to-back was much easier than if we'd been in a side-by-side.
We thought we were going to purchase one, but after trying it in the store and reading reviews on Target.com/BabiesRUs.com, we abandoned it all together and went with the Graco.
We only really used it for about 18 months. Our son, at 3.5 is really too big to sit in it anymore. So, for the sake of cost, I'd almost recommend a less expensive one depending on how frequently you think you're going to use it.
Also consider the space it will take-up in your trunk. Our is pretty compact, but even after taking it to the zoo last weekend, it was tough to have space for all our groceries and the stroller in the back of a large SUV.