Watch the My Pentatonic Blues Rant! online guitar lesson by Rob Garland from Melodic Soloing: Blues Chord Tones
An at early age, we're taught the go-to scale for blues and blues rock is the minor pentatonic. The glaring omission here is that if I took a Gm pentatonic scale and played it against a G7 chord I have a Bb and not a B. Now yes, a lot of blues playing is about tension but there are better ways to build and release tension.
In the context of a G7 blues, the b3rd of minor pentatonic, the note Bb clashes with the major 3rd of the G7 chord, the note B, which is why most blues players tend to bend it.
So, you could move between the major pentatonic and the minor pentatonic on the I chord to the IV, G7 to C7:
Gmaj pentatonic = G A B D E Gmin pentatonic = G Bb C D F
Another option on the G7 is a hybrid pentatonic I call the dominant pentatonic (G B C D F) which contains both the 3rd and b7th (taken from the Mixolydian mode).
For the V chord, D7, you could stay with Gm pentatonic, as it only has one bar and that moves back into C7, (which the Gm pentatonic sounds good against) but I tend to approach a chord tone such as the 3rd of the D7, the note F# and well, that's why I'm making this course! :-]