I still run 32 bit versions, even on my 64 bit hardware. Why? Because I don't need 32bit libraries mixing in with 64 bit apps, and, unless your doing something like compiling code, or, transcoding video files, you won't see that much of a difference in speed. If you want to get around the 3gb restriction on memory, use a PAE kernel, I install them by default now, even though I only have one 8gb machine. The 4 gb machines show full usage, but, I've never seen a whole 4 gb used during any of my sessions.
It's funny that you mentioned adobe, since they've just restricted access to their 64 bit version of flash. Adobe reader is still just a 32 bit app that runs on 64 bit. Even Google Earth & Skype require 32 bit libs to run.
So, when the software developers some out with apps that run on 64 bit natively, I'll switch, but, until then, it's much easier for me to run a 32 bit OS and not worry about 64 bit compatibility.
I totally agree.