A question about optimal route

I would appreciate your thoughts on my daily commute to work. The shortest commute is 19 miles each way, of which there is a 2.5 mile stretch of 30-35 mph with about a dozen traffic lights. On average I get a red light on at least six of those lights. Also, there is considerable traffic in this stretch, making it difficult to coast to a stop and gently speed up from it. The highway/city split is 10 miles/9 miles.

I can take a detour which adds 1.5 miles at 40-45 mph, but has very light traffic, and only about six lights of which I rarely ever get a red light. I can coast and gently ramp up, and also afford to go anywhere between 30-45 mph.

So overall, what are your thoughts on fuel economy of the two routes? Are more stops better than almost no stops? Also, 3 miles of extra mileage every day for a year is about 750 miles. How does that factor in?

Thanks!