Most of my stuff on my Mac is ALAC, most of the music on my PC is FLAC (aside from the oodles of crappy .MP3's I have... urgh)
Bit for Bit > FLAC and ALAC seem to be fairly identical as files and identical to my ears.
ALAC files are a little bit bigger if you like your super HR album art.
I buy music in FLAC and then use the £1 application "FlacTunes" from the app store, it makes another lossless copy of a lossless file and makes it iTunes compatible.
There was an old program called "Fluke" which played FLACs through iTunes. (only on OS X pre Lion (10.7) )
The forever awesome Allesandro Cortini released his Sonoio "Red" album with a dual-download of FLAC and ALAC.
PC-wise, foobar2000 is still the way to go IMHO but as you have an iPod Touch; ALAC is probably where you want to pitch your tent.
You're right there. Alot of download sources are offering ALAC now along with FLAC. HD Tracks is FLAC only still but I bet ALAC is coming very soon. In the meantime, no biggie converting FLAC to ALAC. I use Traders Little Helper (free)