honestly, I was dead set on a wooden set when I started looking for one for DD. Then I took a closer look at the Thomas the Train Trackmaster plastic set primarily b/c of the super cool remote control trains they make for it. DD adores hers and uses it more than she would if we had a simple wooden track, based on how she plays with them at her friends' houses. As I type she has pulled out the track pieces and built her own track circle, only needing help to get the bridge set up. So, don't knock the plastic options. I chose the trains first and then got the matching set of tracks. No regrets here.
Re: Melissa & Doug Deluxe Railway or another train set suggestion
We bought something like this from imaginarium at TRU. It's a ton of track and works perfectly with the thomas stuff.
https://www.amazon.com/Wooden-Compatible-Thomas-Friends-Railway/dp/B0010ODNUY/ref=sr_1_1?s=toys-and-games&ie=UTF8&qid=1298911107&sr=1-1