I thought I saw the Vigoro in Spring with the crabgrass preventer available. As for weed control, use the Weedbgone with a hose end sprayer. You only have to do this once in May before it gets too hot. If you have a large lawn get the concentrate bottle and a separate hose end spray bottle with an adjustable dial but make sure you use the proper setting. Too much will kill your lawn not to mention pets, wildlife, etc.
The Dark green you notice isn't really the best sign of a healthy lawn, just the chemical makeup of the fertilzer(compare the middle number listed on the bags). You could actually be putting too much down leading to ground water pollution. NJ had a very wet summer last year so you may have had a break using 4 heavy applications. Fertilizer and hot dry weather don't mix very well so be careful with the mid-summer application.