I've spectated twice in the Pyranees and really enjoyed it. Like most live sport you don'tget the best views or most up to date info but the atmosphere and sheer close proximity to the riders makes up for it (as it does at football). We stood half way up the Aspin just outside Arreau, watched the blue train ride past at extraordinairy speed, (gratifyingly they were in close to bottom gear but very aggressive cassette by my standards), Robbie McKeown at the back pull a wheelie etc etc then scooted back down the hill into a bar to watch the final climb (up the Tourmalet?? it was 2005) that Armstrong won quite easily.
Next year we were 70 metres from the finish at a Pyraneean ski resort and watched wheelsucker Hincapie outsprint some poor bloke for a stage victory - his first and only in the Tour if I remember correctly. The riders were so close you could have touched them and you see into their eyes and imagine the pain, the tiredness, the desperation.
We also watched sign on Lannemazen in 2004, all very informal, unpretentious, close up etc. Then rode off to watch then 50 km down the road.
Do it, its great.