I am fortunate to live close to Chicago's Lakefront trail. It's a half mile walk (or I should say warm-up) from our condo to the trail at Lake Shore Drive and Fullerton Parkway (photo below). I wait to turn on my Garmin GPS watch until I get close to the lake; all the buildings inland make it harder to acquire the satellite signals.
The walk to the trail feels like the prep before a race. Make sure everything's tied snug, the watch is working, the legs are loose, the hair is snugly secured in the hair tie, etc.
Once you get on the trail it's go time. You hit start on the watch and you start running. In a way it's like getting onto the expressway; you wait for a clear spot in the traffic and then you dart in.
The traffic on the lakefront trail mimics the feel of being in a race. Someone passes you and so you pick up the pace... or you see a girl an eighth of a mile ahead of you with a purple shirt on and you make her your next goal. There's lots to look at, and a lot of ways to track your progress. When I head north there are trees that line the path by the tennis courts near Belmont; I like to count how many steps it takes to get between those perfectly placed trees. 1, 2, 3, 4, 5, 6, 7, 8... eight steps to get from tree A to tree B; next time I'll make it 7 steps. Or maybe every time a bike passes I'll sprint for 10 seconds and try to keep up with him.
Another element that makes running the trail like a race are the Fleet Feet aid stations along the path, where runners pick up their Gatorade or water and scurry along.
The running groups training for Fall marathons also adds to race-like environment. It's good practicing for being in tight congested areas. You'll also get the occasional "keep it up" from the running groups, or high-fives from a random dude carrying a skateboard.
Living in Chicago and running long distances, the lakefront trail is really the best way to go. It mimics a race environment in so many ways and provides a great surface (minus Chicago traffic lights!) to get the bigger miles in.
A great map of Chicago's lakefront trail can be downloaded here (PDF).