Re: Your favourite scale for soloing!
I generally disect the progression and use the appropriate scales focusing on the changes. An easy example: Blues/Rock in the key of G the I, IV, V is G, C, D respectively, so I use the G Blues and Minor Pent, C Blues and Minor Pent, and D Blues/Minor Pent at the changes, often using chromatic notes as passing tones.
In more complex chord progressions with seven chords, I will employ the Mixo since it has the b7 that complements the seven chord.
Before I start school at the Atlanta Institute of Music, I used to just hit notes and figure out later that I was using primarily the minor pent and blues scales. Now schooling has kinda caused me to analyze the progression, identify the neighboring tones and play the changes to really intensify the solo.
If I have never jammed a tune before, though, I find I am inadvertently using the BLues or minor pent scales until I learn the turnarounds just to be safe.