1) Tire Dressing - I prefer the Wet Look Tire dressing from DG because of its durability. I prefer its looks after a wash or after the shine goes away. IMO as far as greasiness is concerned, it's no different than other solvent-based dressings. The difference though is that it lasts quite a bit longer, but unfortunately it's costs also quite a bit more than other dressings. That would be my main reason for not buying it again.
2) Glass - I don't have DG's glass cleaner, but I do have their Rain Repel, which if you read the product description is also considered a glass cleaner. From my understanding, it's supposed to be used on the outside of the glass (for its rain repelling capability) but I often find that if I dry my windows first after a wash, a glass cleaner is not necessary. Also, I don't see much of a difference as far as water repellency goes when compared to just using AquaWax on your glass. If you have AW already, I personally wouldn't bother with Rain Repel.
One difference though is that Rain Repel can be mixed IIRC 1:1 for use in your windshield washer reservoir. So recently I just started using up my Rain Repel for this purpose to get rid of the product. We haven't had any rain lately, but so far it's been a pretty good windshield washer cleaner when diluted with distilled water. I can't say that it's amazing compared to RainX washer fluid or Prestone's washer fluid, but it works just as well if not better from what I can see.