I decided to do some Googling.
It looks like the blue soda glass is indeed depression glass; the Mayfair pattern by Hocking Glass, which is one of the most popular ones and the blue is pretty rare. I looked at eBay sold listing, and it looks like glasses like mine go for upwards of $100.
I guess that was $0.15 well spent!
The yellow piece is also depression glass; the Lorain pattern by Indiana Glass. Not as wow-valuable as the blue, but still, round $15 is nothing to sneeze at when I only paid a quarter!