Blah, I'm still undecided on this bundle, I only have Gemini Rue. Blackwell's 640x400 rez is like so 20 years ago.
Almost all AGS games, including the Blackwell ones, allow you to use a graphics filter to scale the game resolution. Typically there's an executable called winsetup.exe in the same directory as the game (it's actually the same as running the game itself with the --setup flag). Run it, select "Run game in window instead of full-screen", and pick a graphics filter that scales the window resolution to the one you want. The scaling is not perfect, but since these are mostly pixel graphics anyway, it's definitely playable at higher resolutions. I play almost all AGS games like this (some have better looking filters like hqx ones).